diff --git a/mysql-test/main/mysql_connector_net.ps1 b/mysql-test/main/mysql_connector_net.ps1
new file mode 100644
index 00000000000..159acf9361c
--- /dev/null
+++ b/mysql-test/main/mysql_connector_net.ps1
@@ -0,0 +1,58 @@
+$assembly = [system.reflection.Assembly]::LoadWithPartialName("MySql.Data")
+if ($assembly -eq $null)
+{
+  "Can't load assembly MySql.Data"
+  exit 100
+}
+
+try
+{
+  $connectionString =[string]::Format("server=127.0.0.1;uid=root;port={0};Connection Reset=true;",$Env:MASTER_MYPORT)
+  $connection = [MySql.Data.MySqlClient.MySqlConnection]@{ConnectionString=$connectionString}
+  $connection.Open()
+
+  # Test ExecuteReader()
+  $command = New-Object MySql.Data.MySqlClient.MySqlCommand
+  $command.Connection = $connection
+  $command.CommandText = "SELECT @@old_mode"
+  $reader = $command.ExecuteReader()
+  $reader.GetName(0)
+  while ($reader.Read())
+  {
+    $reader.GetValue(0)
+  }
+
+  # Test connection reset
+  $connection.Close()
+  $connection.Open()
+  # Test ExecuteNonQuery()
+  $command.CommandText="do 1";
+  $affected_rows = $command.ExecuteNonQuery()
+  if ($affected_rows -ne 0)
+  {
+    "Expected affected rows 0, actual $affected_rows"
+    exit 1
+  }
+  # Test Prepared Statement
+  $command.CommandText = "SELECT @var";
+  [void]$command.Parameters.AddWithValue("@var", 1);
+  $command.Prepare();
+  $out = $command.ExecuteScalar();
+  if ($out -ne 1)
+  {
+    "Expected output 1, actual $out"
+    exit 1
+  }
+  $connection.Close()
+}
+catch
+{
+  # Dump exception
+  $_
+  $inner = $PSItem.Exception.InnerException
+  if ($inner -ne  $null)
+  {
+    $PSItem.Exception.InnerException.Message
+    $PSItem.Exception.InnerException.StackTrace
+  }
+}
diff --git a/mysql-test/main/mysql_connector_net.result b/mysql-test/main/mysql_connector_net.result
new file mode 100644
index 00000000000..f2fa39df3e7
--- /dev/null
+++ b/mysql-test/main/mysql_connector_net.result
@@ -0,0 +1,2 @@
+@@old_mode
+UTF8_IS_UTF8MB3,NO_NULL_COLLATION_IDS
diff --git a/mysql-test/main/mysql_connector_net.test b/mysql-test/main/mysql_connector_net.test
new file mode 100644
index 00000000000..c1dce65adc8
--- /dev/null
+++ b/mysql-test/main/mysql_connector_net.test
@@ -0,0 +1,11 @@
+--source include/windows.inc
+let $sys_errno=0;
+
+# Error 100 is returned by the powershell script
+# if MySql.Data is not installed
+--error 0,100
+--exec powershell -NoLogo -NoProfile -File main\mysql_connector_net.ps1
+if ($sys_errno != 0)
+{
+  --skip Connector/NET is not installed
+}
diff --git a/mysql-test/main/mysqld--help,win.rdiff b/mysql-test/main/mysqld--help,win.rdiff
index 3e9541d7d2f..a42c0c6f81f 100644
--- a/mysql-test/main/mysqld--help,win.rdiff
+++ b/mysql-test/main/mysqld--help,win.rdiff
@@ -1,4 +1,6 @@
-@@ -180,6 +180,7 @@
+--- main/mysqld--help.result	2023-11-30 02:21:51.951132200 +0100
++++ main/mysqld--help,win.reject	2023-11-30 02:35:44.404612300 +0100
+@@ -191,6 +191,7 @@
   --console           Write error output on screen; don't remove the console
   window on windows.
   --core-file         Write core on crashes
@@ -6,7 +8,7 @@
   -h, --datadir=name  Path to the database root directory
   --date-format=name  The DATE format (ignored)
   --datetime-format=name 
-@@ -650,6 +651,7 @@
+@@ -696,6 +697,7 @@
   Use MySQL-5.6 (instead of MariaDB-5.3) format for TIME,
   DATETIME, TIMESTAMP columns.
   (Defaults to on; use --skip-mysql56-temporal-format to disable.)
@@ -14,7 +16,7 @@
   --net-buffer-length=# 
   Buffer length for TCP/IP and socket communication
   --net-read-timeout=# 
-@@ -1327,6 +1328,10 @@
+@@ -1351,6 +1353,10 @@
   Alias for log_slow_query_file. Log slow queries to given
   log file. Defaults logging to 'hostname'-slow.log. Must
   be enabled to activate other slow log options
@@ -25,7 +27,7 @@
   --socket=name       Socket file to use for connection
   --sort-buffer-size=# 
   Each thread that needs to do a sort allocates a buffer of
-@@ -1351,6 +1356,7 @@
+@@ -1376,6 +1382,7 @@
   deleting or updating every row in a table.
   --stack-trace       Print a symbolic stack trace on failure
   (Defaults to on; use --skip-stack-trace to disable.)
@@ -33,7 +35,7 @@
   --standard-compliant-cte 
   Allow only CTEs compliant to SQL standard
   (Defaults to on; use --skip-standard-compliant-cte to disable.)
-@@ -1426,6 +1432,11 @@
+@@ -1454,6 +1461,11 @@
   --thread-pool-max-threads=# 
   Maximum allowed number of worker threads in the thread
   pool
@@ -45,7 +47,7 @@
   --thread-pool-oversubscribe=# 
   How many additional active worker threads in a group are
   allowed.
-@@ -1464,8 +1475,8 @@
+@@ -1493,8 +1505,8 @@
   automatically convert it to an on-disk MyISAM or Aria
   table.
   -t, --tmpdir=name   Path for temporary files. Several paths may be specified,
@@ -56,7 +58,7 @@
   --transaction-alloc-block-size=# 
   Allocation block size for transactions to be stored in
   binary log
-@@ -1685,6 +1696,7 @@
+@@ -1716,6 +1728,7 @@
  myisam-stats-method NULLS_UNEQUAL
  myisam-use-mmap FALSE
  mysql56-temporal-format TRUE
@@ -64,7 +66,7 @@
  net-buffer-length 16384
  net-read-timeout 30
  net-retry-count 10
-@@ -1841,6 +1853,7 @@
+@@ -1874,6 +1887,7 @@
  slave-type-conversions 
  slow-launch-time 2
  slow-query-log FALSE
@@ -72,7 +74,7 @@
  sort-buffer-size 2097152
  sql-mode STRICT_TRANS_TABLES,ERROR_FOR_DIVISION_BY_ZERO,NO_AUTO_CREATE_USER,NO_ENGINE_SUBSTITUTION
  sql-safe-updates FALSE
-@@ -1867,6 +1880,8 @@
+@@ -1901,6 +1915,8 @@
  thread-pool-exact-stats FALSE
  thread-pool-idle-timeout 60
  thread-pool-max-threads 65536
diff --git a/mysql-test/main/mysqld--help.result b/mysql-test/main/mysqld--help.result
index 7295493a380..4a95d4c44f8 100644
--- a/mysql-test/main/mysqld--help.result
+++ b/mysql-test/main/mysqld--help.result
@@ -721,7 +721,8 @@ The following specify which files/extra groups are read (specified before remain
  MySQL versions. Any combination of: 
  NO_DUP_KEY_WARNINGS_WITH_IGNORE, NO_PROGRESS_INFO, 
  ZERO_DATE_TIME_CAST, UTF8_IS_UTF8MB3, 
- IGNORE_INDEX_ONLY_FOR_JOIN, COMPAT_5_1_CHECKSUM
+ IGNORE_INDEX_ONLY_FOR_JOIN, COMPAT_5_1_CHECKSUM, 
+ NO_NULL_COLLATION_IDS
  Use 'ALL' to set all combinations.
  --old-passwords     Use old password encryption method (needed for 4.0 and
  older clients)
diff --git a/mysql-test/main/old-mode.result b/mysql-test/main/old-mode.result
index daa2a4dc915..cb87c45ada8 100644
--- a/mysql-test/main/old-mode.result
+++ b/mysql-test/main/old-mode.result
@@ -257,3 +257,13 @@ Warning	1264	Out of range value for column 'a' at row 2
 DROP TABLE t1;
 SET @@time_zone=DEFAULT;
 SET TIMESTAMP=DEFAULT;
+#
+# MDEV-31608 - Connector/NET fails to connect since 10.10
+#
+select count(*) > 0 from information_schema.collations where id IS NULL;
+count(*) > 0
+1
+SET old_mode=no_null_collation_ids;
+select count(*) > 0 from information_schema.collations where id IS NULL;
+count(*) > 0
+0
diff --git a/mysql-test/main/old-mode.test b/mysql-test/main/old-mode.test
index e4928329b47..177e00edce8 100644
--- a/mysql-test/main/old-mode.test
+++ b/mysql-test/main/old-mode.test
@@ -169,3 +169,11 @@ DROP TABLE t1;
 
 SET @@time_zone=DEFAULT;
 SET TIMESTAMP=DEFAULT;
+
+--echo #
+--echo # MDEV-31608 - Connector/NET fails to connect since 10.10
+--echo #
+select count(*) > 0 from information_schema.collations where id IS NULL;
+SET old_mode=no_null_collation_ids;
+select count(*) > 0 from information_schema.collations where id IS NULL;
+
diff --git a/mysql-test/suite/innodb/r/innodb-blob.result b/mysql-test/suite/innodb/r/innodb-blob.result
index 63c52f2e6e5..f5daacf938e 100644
--- a/mysql-test/suite/innodb/r/innodb-blob.result
+++ b/mysql-test/suite/innodb/r/innodb-blob.result
@@ -20,8 +20,6 @@ a	RIGHT(b,20)
 2	bbbbbbbbbbbbbbbbbbbb
 connection default;
 SET DEBUG='+d,row_ins_extern_checkpoint';
-Warnings:
-Warning	1287	'@@debug' is deprecated and will be removed in a future release. Please use '@@debug_dbug' instead
 SET DEBUG_SYNC='before_row_ins_extern_latch SIGNAL rec_not_blob WAIT_FOR crash';
 ROLLBACK;
 BEGIN;
@@ -88,8 +86,6 @@ BEGIN;
 INSERT INTO t2 VALUES (347);
 connection default;
 SET DEBUG='+d,row_upd_extern_checkpoint';
-Warnings:
-Warning	1287	'@@debug' is deprecated and will be removed in a future release. Please use '@@debug_dbug' instead
 SET DEBUG_SYNC='before_row_upd_extern SIGNAL have_latch WAIT_FOR crash';
 UPDATE t3 SET c=REPEAT('i',3000) WHERE a=2;
 connection con2;
@@ -126,8 +122,6 @@ BEGIN;
 INSERT INTO t2 VALUES (33101);
 connection default;
 SET DEBUG='+d,row_upd_extern_checkpoint';
-Warnings:
-Warning	1287	'@@debug' is deprecated and will be removed in a future release. Please use '@@debug_dbug' instead
 SET DEBUG_SYNC='after_row_upd_extern SIGNAL have_latch WAIT_FOR crash';
 UPDATE t3 SET c=REPEAT('j',3000) WHERE a=2;
 connection con2;
diff --git a/mysql-test/suite/innodb/r/innodb-index-debug.result b/mysql-test/suite/innodb/r/innodb-index-debug.result
index 0995b526821..7167a80f3cb 100644
--- a/mysql-test/suite/innodb/r/innodb-index-debug.result
+++ b/mysql-test/suite/innodb/r/innodb-index-debug.result
@@ -92,8 +92,6 @@ ALTER TABLE t1 FORCE, ADD COLUMN k4 int;
 connection default;
 SET DEBUG_SYNC= 'now WAIT_FOR opened';
 SET debug = '+d,row_log_tmpfile_fail';
-Warnings:
-Warning	1287	'@@debug' is deprecated and will be removed in a future release. Please use '@@debug_dbug' instead
 INSERT INTO t1 select NULL,'aaa','bbb' from t480;
 INSERT INTO t1 select NULL,'aaaa','bbbb' from t480;
 SET DEBUG_SYNC= 'now SIGNAL flushed';
diff --git a/mysql-test/suite/innodb/r/innodb-table-online.result b/mysql-test/suite/innodb/r/innodb-table-online.result
index 17ab02e3ec4..68be3f0e43b 100644
--- a/mysql-test/suite/innodb/r/innodb-table-online.result
+++ b/mysql-test/suite/innodb/r/innodb-table-online.result
@@ -36,16 +36,10 @@ SET DEBUG_DBUG = '+d,innodb_OOM_prepare_inplace_alter';
 ALTER TABLE t1 ROW_FORMAT=REDUNDANT, ALGORITHM=INPLACE, LOCK=NONE;
 ERROR HY000: Out of memory.
 SET SESSION DEBUG = @saved_debug_dbug;
-Warnings:
-Warning	1287	'@@debug' is deprecated and will be removed in a future release. Please use '@@debug_dbug' instead
 SET SESSION DEBUG = '+d,innodb_OOM_inplace_alter';
-Warnings:
-Warning	1287	'@@debug' is deprecated and will be removed in a future release. Please use '@@debug_dbug' instead
 ALTER TABLE t1 ROW_FORMAT=REDUNDANT, ALGORITHM=INPLACE, LOCK=NONE;
 ERROR HY000: Out of memory.
 SET SESSION DEBUG = @saved_debug_dbug;
-Warnings:
-Warning	1287	'@@debug' is deprecated and will be removed in a future release. Please use '@@debug_dbug' instead
 ALTER TABLE t1 ROW_FORMAT=REDUNDANT, ALGORITHM=INPLACE, LOCK=NONE;
 connection default;
 SHOW CREATE TABLE t1;
diff --git a/mysql-test/suite/innodb/r/page_reorganize.result b/mysql-test/suite/innodb/r/page_reorganize.result
index 20e1600bd0d..fe85926e2b8 100644
--- a/mysql-test/suite/innodb/r/page_reorganize.result
+++ b/mysql-test/suite/innodb/r/page_reorganize.result
@@ -16,8 +16,6 @@ SET @save_dbug = @@debug_dbug;
 SET DEBUG_DBUG = '+d,do_page_reorganize,do_lock_reverse_page_reorganize';
 insert into t1(f2) values (repeat('+', 100));
 SET DEBUG = @save_dbug;
-Warnings:
-Warning	1287	'@@debug' is deprecated and will be removed in a future release. Please use '@@debug_dbug' instead
 commit;
 connection con1;
 f1
diff --git a/mysql-test/suite/innodb_fts/r/ft_result_cache_limit.result b/mysql-test/suite/innodb_fts/r/ft_result_cache_limit.result
index 2dbdd5a04bc..74d60410d58 100644
--- a/mysql-test/suite/innodb_fts/r/ft_result_cache_limit.result
+++ b/mysql-test/suite/innodb_fts/r/ft_result_cache_limit.result
@@ -20,8 +20,6 @@ END//
 CALL populate_t1;
 SET autocommit=1;
 SET SESSION debug="+d,fts_instrument_result_cache_limit";
-Warnings:
-Warning	1287	'@@debug' is deprecated and will be removed in a future release. Please use '@@debug_dbug' instead
 ALTER TABLE t1 ADD FULLTEXT INDEX `text_content_idx` (`text_content`);
 SELECT FTS_DOC_ID, text_content
 FROM t1
diff --git a/mysql-test/suite/innodb_gis/r/check_rtree.result b/mysql-test/suite/innodb_gis/r/check_rtree.result
index fe60a628fde..0d7b25b6b72 100644
--- a/mysql-test/suite/innodb_gis/r/check_rtree.result
+++ b/mysql-test/suite/innodb_gis/r/check_rtree.result
@@ -1,7 +1,5 @@
 create table t1 (i int, g geometry not null, spatial index (g))engine=innodb;
 SET SESSION debug="+d,rtree_test_check_count";
-Warnings:
-Warning	1287	'@@debug' is deprecated and will be removed in a future release. Please use '@@debug_dbug' instead
 insert into t1 values (1, POINT(1,1));
 insert into t1 values (1, POINT(1.5,1.5));
 insert into t1 values (1, POINT(3,3));
diff --git a/mysql-test/suite/innodb_gis/r/rollback.result b/mysql-test/suite/innodb_gis/r/rollback.result
index 0d2b9c7cf2c..1efe5d284f7 100644
--- a/mysql-test/suite/innodb_gis/r/rollback.result
+++ b/mysql-test/suite/innodb_gis/r/rollback.result
@@ -408,8 +408,6 @@ update t1 set a=point(5,5), b=point(5,5), c=5 where i < 3;
 ERROR 23000: Duplicate entry '5' for key 'c'
 rollback;
 set session debug="+d,row_mysql_crash_if_error";
-Warnings:
-Warning	1287	'@@debug' is deprecated and will be removed in a future release. Please use '@@debug_dbug' instead
 update t1 set a=point(5,5), b=point(5,5), c=5 where i < 3;
 ERROR HY000: Lost connection to server during query
 insert into t1 values(5, point(5,5), point(5,5), 5);
diff --git a/mysql-test/suite/innodb_gis/r/rtree_compress.result b/mysql-test/suite/innodb_gis/r/rtree_compress.result
index db9d5bd634c..9b646985dd4 100644
--- a/mysql-test/suite/innodb_gis/r/rtree_compress.result
+++ b/mysql-test/suite/innodb_gis/r/rtree_compress.result
@@ -44,8 +44,6 @@ count(*)
 0
 SET @saved_dbug = @@SESSION.debug_dbug;
 SET DEBUG='+d,page_copy_rec_list_start_compress_fail';
-Warnings:
-Warning	1287	'@@debug' is deprecated and will be removed in a future release. Please use '@@debug_dbug' instead
 delete from t1;
 select count(*) from t1 where MBRWithin(t1.c2, @g1);
 count(*)
diff --git a/mysql-test/suite/innodb_gis/r/rtree_create_inplace.result b/mysql-test/suite/innodb_gis/r/rtree_create_inplace.result
index a8898f5c98f..5279eea8aa8 100644
--- a/mysql-test/suite/innodb_gis/r/rtree_create_inplace.result
+++ b/mysql-test/suite/innodb_gis/r/rtree_create_inplace.result
@@ -31,7 +31,5 @@ COUNT(*)
 0
 ALTER TABLE t1 DROP INDEX idx, ADD SPATIAL INDEX idx3(c2);
 SET SESSION debug="+d,row_merge_instrument_log_check_flush";
-Warnings:
-Warning	1287	'@@debug' is deprecated and will be removed in a future release. Please use '@@debug_dbug' instead
 ALTER TABLE t1  DROP INDEX idx3, ADD SPATIAL INDEX idx4(c2), ADD SPATIAL INDEX idx5(c3);
 DROP TABLE t1;
diff --git a/mysql-test/suite/perfschema/r/sxlock_func,debug.rdiff b/mysql-test/suite/perfschema/r/sxlock_func,debug.rdiff
new file mode 100644
index 00000000000..0596810e553
--- /dev/null
+++ b/mysql-test/suite/perfschema/r/sxlock_func,debug.rdiff
@@ -0,0 +1,22 @@
+@@ -7,7 +7,6 @@
+ WHERE name LIKE 'wait/synch/rwlock/innodb/%'
+ AND name!='wait/synch/rwlock/innodb/btr_search_latch' ORDER BY name;
+ name
+-wait/synch/rwlock/innodb/dict_operation_lock
+ wait/synch/rwlock/innodb/fil_space_latch
+ wait/synch/rwlock/innodb/lock_latch
+ wait/synch/rwlock/innodb/trx_i_s_cache_lock
+@@ -19,11 +18,13 @@
+ select name from performance_schema.setup_instruments
+ where name like "wait/synch/sxlock/%" order by name;
+ name
++wait/synch/sxlock/innodb/dict_operation_lock
+ wait/synch/sxlock/innodb/index_tree_rw_lock
+ SELECT DISTINCT name FROM performance_schema.rwlock_instances
+ WHERE name LIKE 'wait/synch/sxlock/innodb/%'
+ ORDER BY name;
+ name
++wait/synch/sxlock/innodb/dict_operation_lock
+ wait/synch/sxlock/innodb/index_tree_rw_lock
+ create table t1(a int) engine=innodb;
+ begin;
diff --git a/mysql-test/suite/perfschema/t/sxlock_func.test b/mysql-test/suite/perfschema/t/sxlock_func.test
index c43adc849d2..24d0e07ca41 100644
--- a/mysql-test/suite/perfschema/t/sxlock_func.test
+++ b/mysql-test/suite/perfschema/t/sxlock_func.test
@@ -5,6 +5,7 @@
 --source include/not_embedded.inc
 --source include/have_perfschema.inc
 --source include/have_innodb.inc
+--source include/maybe_debug.inc
 
 UPDATE performance_schema.setup_instruments SET enabled = 'NO', timed = 'YES';
 
diff --git a/mysql-test/suite/rpl/r/rpl_semisync_ali_issues.result b/mysql-test/suite/rpl/r/rpl_semisync_ali_issues.result
index 36a2bac5838..530bbac633b 100644
--- a/mysql-test/suite/rpl/r/rpl_semisync_ali_issues.result
+++ b/mysql-test/suite/rpl/r/rpl_semisync_ali_issues.result
@@ -270,16 +270,12 @@ Variable_name	Value
 Rpl_semi_sync_master_clients	1
 # Test failure of select error .
 SET GLOBAL debug = 'd,rpl_semisync_simulate_select_error';
-Warnings:
-Warning	1287	'@@debug' is deprecated and will be removed in a future release. Please use '@@debug_dbug' instead
 INSERT INTO t1 VALUES(3);
 connection slave;
 connection con1;
 # Test failure of pthread_create
 SET GLOBAL rpl_semi_sync_master_enabled = 0;
 SET GLOBAL debug = 'd,rpl_semisync_simulate_create_thread_failure';
-Warnings:
-Warning	1287	'@@debug' is deprecated and will be removed in a future release. Please use '@@debug_dbug' instead
 SET GLOBAL rpl_semi_sync_master_enabled= ON;
 # Test failure of pthread_join
 SET GLOBAL rpl_semi_sync_master_enabled= OFF;
@@ -287,8 +283,6 @@ SET GLOBAL rpl_semi_sync_master_enabled= OFF;
 # Failure on registering semisync slave
 #
 SET GLOBAL debug= 'd,rpl_semisync_simulate_add_slave_failure';
-Warnings:
-Warning	1287	'@@debug' is deprecated and will be removed in a future release. Please use '@@debug_dbug' instead
 SET GLOBAL rpl_semi_sync_master_enabled= ON;
 connection slave;
 STOP SLAVE IO_THREAD;
@@ -297,8 +291,6 @@ START SLAVE IO_THREAD;
 include/wait_for_slave_io_to_start.inc
 connection con1;
 SET GLOBAL debug='';
-Warnings:
-Warning	1287	'@@debug' is deprecated and will be removed in a future release. Please use '@@debug_dbug' instead
 connection slave;
 START SLAVE IO_THREAD;
 include/wait_for_slave_io_to_start.inc
diff --git a/mysql-test/suite/sys_vars/r/debug_basic.result b/mysql-test/suite/sys_vars/r/debug_basic.result
index a97ad65b40f..5a77446d036 100644
--- a/mysql-test/suite/sys_vars/r/debug_basic.result
+++ b/mysql-test/suite/sys_vars/r/debug_basic.result
@@ -1,6 +1,4 @@
 set session debug="L";
-Warnings:
-Warning	1287	'@@debug' is deprecated and will be removed in a future release. Please use '@@debug_dbug' instead
 select @@global.debug="1";
 @@global.debug="1"
 0
diff --git a/mysql-test/suite/sys_vars/r/old_mode_basic.result b/mysql-test/suite/sys_vars/r/old_mode_basic.result
index 252316dc1cb..776d45a1fe3 100644
--- a/mysql-test/suite/sys_vars/r/old_mode_basic.result
+++ b/mysql-test/suite/sys_vars/r/old_mode_basic.result
@@ -114,8 +114,8 @@ SET @@global.old_mode = 4;
 SELECT @@global.old_mode;
 @@global.old_mode
 ZERO_DATE_TIME_CAST
-SET @@global.old_mode = 64;
-ERROR 42000: Variable 'old_mode' can't be set to the value of '64'
+SET @@global.old_mode = 128;
+ERROR 42000: Variable 'old_mode' can't be set to the value of '128'
 SELECT @@global.old_mode;
 @@global.old_mode
 ZERO_DATE_TIME_CAST
diff --git a/mysql-test/suite/sys_vars/r/sysvars_debug.result b/mysql-test/suite/sys_vars/r/sysvars_debug.result
index fc04ac83210..01f74170b1d 100644
--- a/mysql-test/suite/sys_vars/r/sysvars_debug.result
+++ b/mysql-test/suite/sys_vars/r/sysvars_debug.result
@@ -38,7 +38,7 @@ GLOBAL_VALUE_ORIGIN	COMPILE-TIME
 DEFAULT_VALUE	
 VARIABLE_SCOPE	SESSION
 VARIABLE_TYPE	VARCHAR
-VARIABLE_COMMENT	Built-in DBUG debugger
+VARIABLE_COMMENT	Built-in DBUG debugger. Alias for --debug
 NUMERIC_MIN_VALUE	NULL
 NUMERIC_MAX_VALUE	NULL
 NUMERIC_BLOCK_SIZE	NULL
diff --git a/mysql-test/suite/sys_vars/r/sysvars_server_embedded.result b/mysql-test/suite/sys_vars/r/sysvars_server_embedded.result
index 9450d4c7a6a..a7e144739eb 100644
--- a/mysql-test/suite/sys_vars/r/sysvars_server_embedded.result
+++ b/mysql-test/suite/sys_vars/r/sysvars_server_embedded.result
@@ -2299,7 +2299,7 @@ VARIABLE_COMMENT	Used to emulate old behavior from earlier MariaDB or MySQL vers
 NUMERIC_MIN_VALUE	NULL
 NUMERIC_MAX_VALUE	NULL
 NUMERIC_BLOCK_SIZE	NULL
-ENUM_VALUE_LIST	NO_DUP_KEY_WARNINGS_WITH_IGNORE,NO_PROGRESS_INFO,ZERO_DATE_TIME_CAST,UTF8_IS_UTF8MB3,IGNORE_INDEX_ONLY_FOR_JOIN,COMPAT_5_1_CHECKSUM
+ENUM_VALUE_LIST	NO_DUP_KEY_WARNINGS_WITH_IGNORE,NO_PROGRESS_INFO,ZERO_DATE_TIME_CAST,UTF8_IS_UTF8MB3,IGNORE_INDEX_ONLY_FOR_JOIN,COMPAT_5_1_CHECKSUM,NO_NULL_COLLATION_IDS
 READ_ONLY	NO
 COMMAND_LINE_ARGUMENT	REQUIRED
 VARIABLE_NAME	OLD_PASSWORDS
diff --git a/mysql-test/suite/sys_vars/r/sysvars_server_notembedded.result b/mysql-test/suite/sys_vars/r/sysvars_server_notembedded.result
index f22f670fc01..2b003632dd6 100644
--- a/mysql-test/suite/sys_vars/r/sysvars_server_notembedded.result
+++ b/mysql-test/suite/sys_vars/r/sysvars_server_notembedded.result
@@ -2469,7 +2469,7 @@ VARIABLE_COMMENT	Used to emulate old behavior from earlier MariaDB or MySQL vers
 NUMERIC_MIN_VALUE	NULL
 NUMERIC_MAX_VALUE	NULL
 NUMERIC_BLOCK_SIZE	NULL
-ENUM_VALUE_LIST	NO_DUP_KEY_WARNINGS_WITH_IGNORE,NO_PROGRESS_INFO,ZERO_DATE_TIME_CAST,UTF8_IS_UTF8MB3,IGNORE_INDEX_ONLY_FOR_JOIN,COMPAT_5_1_CHECKSUM
+ENUM_VALUE_LIST	NO_DUP_KEY_WARNINGS_WITH_IGNORE,NO_PROGRESS_INFO,ZERO_DATE_TIME_CAST,UTF8_IS_UTF8MB3,IGNORE_INDEX_ONLY_FOR_JOIN,COMPAT_5_1_CHECKSUM,NO_NULL_COLLATION_IDS
 READ_ONLY	NO
 COMMAND_LINE_ARGUMENT	REQUIRED
 VARIABLE_NAME	OLD_PASSWORDS
diff --git a/mysql-test/suite/sys_vars/t/old_mode_basic.test b/mysql-test/suite/sys_vars/t/old_mode_basic.test
index 631d638767f..cb18796729e 100644
--- a/mysql-test/suite/sys_vars/t/old_mode_basic.test
+++ b/mysql-test/suite/sys_vars/t/old_mode_basic.test
@@ -172,7 +172,7 @@ SET @@global.old_mode = 4;
 SELECT @@global.old_mode;
 
 --Error ER_WRONG_VALUE_FOR_VAR
-SET @@global.old_mode = 64;
+SET @@global.old_mode = 128;
 SELECT @@global.old_mode;
 
 # use of decimal values
diff --git a/plugin/type_inet/mysql-test/type_inet/type_inet6.result b/plugin/type_inet/mysql-test/type_inet/type_inet6.result
index 1d0f77ecbf5..a576a7e163f 100644
--- a/plugin/type_inet/mysql-test/type_inet/type_inet6.result
+++ b/plugin/type_inet/mysql-test/type_inet/type_inet6.result
@@ -2284,6 +2284,81 @@ Warnings:
 Warning	1292	Incorrect inet6 value: ''
 DROP TABLE t1;
 #
+# MDEV-32879 Server crash in my_decimal::operator= or unexpected ER_DUP_ENTRY upon comparison with INET6 and similar types
+#
+CREATE TABLE t1 (a CHAR(36) NOT NULL, b INET6 NOT NULL, c DATETIME(6) NOT NULL);
+INSERT INTO t1 VALUES ('','::','2000-01-01'),('','::','1900-01-01');
+SELECT c + (b = a) AS f, GROUP_CONCAT(c) FROM t1 GROUP BY f;
+f	GROUP_CONCAT(c)
+NULL	2000-01-01 00:00:00.000000,1900-01-01 00:00:00.000000
+Warnings:
+Warning	1292	Incorrect inet6 value: ''
+Warning	1292	Incorrect inet6 value: ''
+Warning	1292	Incorrect inet6 value: ''
+Warning	1292	Incorrect inet6 value: ''
+Warning	1292	Incorrect inet6 value: ''
+DROP TABLE t1;
+CREATE TABLE t1 (a CHAR(36) NOT NULL, b INET6 NOT NULL, c DATETIME(6) NOT NULL);
+INSERT INTO t1 VALUES ('','::','2000-01-01'),('','::','1900-01-01');
+SELECT c + (b = a) AS f, COUNT(c) FROM t1 GROUP BY f;
+f	COUNT(c)
+NULL	2
+Warnings:
+Warning	1292	Incorrect inet6 value: ''
+Warning	1292	Incorrect inet6 value: ''
+Warning	1292	Incorrect inet6 value: ''
+DROP TABLE t1;
+CREATE OR REPLACE TABLE t1 (a CHAR(36) NOT NULL, b INET6 NOT NULL, c DATETIME(6) NOT NULL);
+INSERT INTO t1 VALUES ('','::','2000-01-01'),('','::','1900-01-01');
+SELECT c + (b = a) AS f FROM t1 ORDER BY f;
+f
+NULL
+NULL
+Warnings:
+Warning	1292	Incorrect inet6 value: ''
+Warning	1292	Incorrect inet6 value: ''
+Warning	1292	Incorrect inet6 value: ''
+Warning	1292	Incorrect inet6 value: ''
+DROP TABLE t1;
+CREATE OR REPLACE TABLE t1 (a CHAR(36) NOT NULL, b INET6 NOT NULL);
+INSERT INTO t1 VALUES ('','::'),('','::');
+SELECT 1.00 + (b = a) AS f FROM t1 ORDER BY f;
+f
+NULL
+NULL
+Warnings:
+Warning	1292	Incorrect inet6 value: ''
+Warning	1292	Incorrect inet6 value: ''
+Warning	1292	Incorrect inet6 value: ''
+Warning	1292	Incorrect inet6 value: ''
+SELECT 1.00 + (b BETWEEN a AND '') AS f FROM t1 ORDER BY f;
+f
+NULL
+NULL
+Warnings:
+Warning	1292	Incorrect inet6 value: ''
+Warning	1292	Incorrect inet6 value: ''
+Warning	1292	Incorrect inet6 value: ''
+Warning	1292	Incorrect inet6 value: ''
+Warning	1292	Incorrect inet6 value: ''
+Warning	1292	Incorrect inet6 value: ''
+Warning	1292	Incorrect inet6 value: ''
+Warning	1292	Incorrect inet6 value: ''
+SELECT 1.00 + (b IN (a,'')) AS f FROM t1 ORDER BY f;
+f
+NULL
+NULL
+Warnings:
+Warning	1292	Incorrect inet6 value: ''
+Warning	1292	Incorrect inet6 value: ''
+Warning	1292	Incorrect inet6 value: ''
+Warning	1292	Incorrect inet6 value: ''
+Warning	1292	Incorrect inet6 value: ''
+Warning	1292	Incorrect inet6 value: ''
+Warning	1292	Incorrect inet6 value: ''
+Warning	1292	Incorrect inet6 value: ''
+DROP TABLE t1;
+#
 # MDEV-22256 Assertion `length == pack_length()' failed in Field_timestamp_with_dec::sort_string
 #
 SET sql_mode='';
diff --git a/plugin/type_inet/mysql-test/type_inet/type_inet6.test b/plugin/type_inet/mysql-test/type_inet/type_inet6.test
index 99f75312f3c..0c56ecfe4bb 100644
--- a/plugin/type_inet/mysql-test/type_inet/type_inet6.test
+++ b/plugin/type_inet/mysql-test/type_inet/type_inet6.test
@@ -1675,6 +1675,32 @@ INSERT INTO t1 VALUES ('::');
 SELECT * FROM t1 WHERE a IN ('','::1');
 DROP TABLE t1;
 
+--echo #
+--echo # MDEV-32879 Server crash in my_decimal::operator= or unexpected ER_DUP_ENTRY upon comparison with INET6 and similar types
+--echo #
+
+CREATE TABLE t1 (a CHAR(36) NOT NULL, b INET6 NOT NULL, c DATETIME(6) NOT NULL);
+INSERT INTO t1 VALUES ('','::','2000-01-01'),('','::','1900-01-01');
+SELECT c + (b = a) AS f, GROUP_CONCAT(c) FROM t1 GROUP BY f;
+DROP TABLE t1;
+
+CREATE TABLE t1 (a CHAR(36) NOT NULL, b INET6 NOT NULL, c DATETIME(6) NOT NULL);
+INSERT INTO t1 VALUES ('','::','2000-01-01'),('','::','1900-01-01');
+SELECT c + (b = a) AS f, COUNT(c) FROM t1 GROUP BY f;
+DROP TABLE t1;
+
+CREATE OR REPLACE TABLE t1 (a CHAR(36) NOT NULL, b INET6 NOT NULL, c DATETIME(6) NOT NULL);
+INSERT INTO t1 VALUES ('','::','2000-01-01'),('','::','1900-01-01');
+SELECT c + (b = a) AS f FROM t1 ORDER BY f;
+DROP TABLE t1;
+
+CREATE OR REPLACE TABLE t1 (a CHAR(36) NOT NULL, b INET6 NOT NULL);
+INSERT INTO t1 VALUES ('','::'),('','::');
+SELECT 1.00 + (b = a) AS f FROM t1 ORDER BY f;
+SELECT 1.00 + (b BETWEEN a AND '') AS f FROM t1 ORDER BY f;
+SELECT 1.00 + (b IN (a,'')) AS f FROM t1 ORDER BY f;
+DROP TABLE t1;
+
 --echo #
 --echo # MDEV-22256 Assertion `length == pack_length()' failed in Field_timestamp_with_dec::sort_string
 --echo #
diff --git a/scripts/mysql_setpermission.sh b/scripts/mysql_setpermission.sh
index 76c07b6816b..9af895ff8b8 100644
--- a/scripts/mysql_setpermission.sh
+++ b/scripts/mysql_setpermission.sh
@@ -71,7 +71,7 @@ usage() if ($opt_help); # the help function
 
 if ($opt_host =~ s/:(\d+)$//)
 {
-    $opt_port = $1;
+  $opt_port = $1;
 }
 
 if ($opt_host eq '')
@@ -101,7 +101,7 @@ my $prefix= 'mysql';
 if (eval {DBI->install_driver("MariaDB")}) {
   $dsn ="DBI:MariaDB:;";
   $prefix= 'mariadb';
-} 
+}
 else {
   $dsn = "DBI:mysql:;";
 }
@@ -229,11 +229,11 @@ sub setpwd
   {
     $pass = "PASSWORD(". $dbh->quote($pass) . ")";
   }
-  my $uh= "$user@$host";
+  my $uh= $user."@".$host;
   my $sth = $dbh->prepare("set password for $uh =$pass") || die $dbh->errstr;
   $sth->execute || die $dbh->errstr;
   $sth->finish;
-  print "The password is set for user $user.\n\n";
+  print "The password is set for user $uh.\n\n";
 
 }
 
diff --git a/sql/item_cmpfunc.cc b/sql/item_cmpfunc.cc
index 387484a37ff..ae86383ac2e 100644
--- a/sql/item_cmpfunc.cc
+++ b/sql/item_cmpfunc.cc
@@ -457,40 +457,6 @@ void Item_bool_func::raise_note_if_key_become_unused(THD *thd, const Item_args &
 }
 
 
-bool Item_func::setup_args_and_comparator(THD *thd, Arg_comparator *cmp)
-{
-  DBUG_ASSERT(arg_count >= 2); // Item_func_nullif has arg_count == 3
-
-  if (args[0]->cmp_type() == STRING_RESULT &&
-      args[1]->cmp_type() == STRING_RESULT)
-  {
-    CHARSET_INFO *tmp;
-    /*
-      Use charset narrowing only for equalities, as that would allow
-      to construct ref access.
-      Non-equality comparisons with constants work without charset narrowing,
-      the constant gets converted.
-      Non-equality comparisons with non-constants would need narrowing to
-      enable range optimizer to handle e.g.
-        t1.mb3key_col <= const_table.mb4_col
-      But this doesn't look important.
-    */
-    bool allow_narrowing= MY_TEST(functype()==Item_func::EQ_FUNC ||
-                                  functype()==Item_func::EQUAL_FUNC);
-
-    if (agg_arg_charsets_for_comparison(&tmp, &args[0], &args[1],
-                                        allow_narrowing))
-      return true;
-    cmp->m_compare_collation= tmp;
-  }
-  //  Convert constants when compared to int/year field
-  DBUG_ASSERT(functype() != LIKE_FUNC);
-  convert_const_compared_to_int_field(thd);
-
-  return cmp->set_cmp_func(thd, this, &args[0], &args[1], true);
-}
-
-
 /*
   Comparison operators remove arguments' dependency on PAD_CHAR_TO_FULL_LENGTH
   in case of PAD SPACE comparison collations: trailing spaces do not affect
@@ -519,8 +485,15 @@ bool Item_bool_rowready_func2::fix_length_and_dec(THD *thd)
   if (!args[0] || !args[1])
     return FALSE;
   Item_args old_args(args[0], args[1]);
-  if (setup_args_and_comparator(thd, &cmp))
+  convert_const_compared_to_int_field(thd);
+  Type_handler_hybrid_field_type tmp;
+  if (tmp.aggregate_for_comparison(func_name_cstring(), args, 2, false) ||
+      tmp.type_handler()->Item_bool_rowready_func2_fix_length_and_dec(thd,
+                                                                      this))
+  {
+    DBUG_ASSERT(thd->is_error());
     return true;
+  }
   raise_note_if_key_become_unused(thd, old_args);
   return false;
 }
@@ -540,21 +513,14 @@ bool Item_bool_rowready_func2::fix_length_and_dec(THD *thd)
 */
 
 int Arg_comparator::set_cmp_func(THD *thd, Item_func_or_sum *owner_arg,
+                                 const Type_handler *compare_handler,
                                  Item **a1, Item **a2)
 {
   owner= owner_arg;
   set_null= set_null && owner_arg;
   a= a1;
   b= a2;
-  Item *tmp_args[2]= {*a1, *a2};
-  Type_handler_hybrid_field_type tmp;
-  if (tmp.aggregate_for_comparison(owner_arg->func_name_cstring(), tmp_args, 2,
-                                   false))
-  {
-    DBUG_ASSERT(thd->is_error());
-    return 1;
-  }
-  m_compare_handler= tmp.type_handler();
+  m_compare_handler= compare_handler;
   return m_compare_handler->set_comparator_func(thd, this);
 }
 
@@ -605,6 +571,14 @@ bool Arg_comparator::set_cmp_func_string(THD *thd)
       We must set cmp_collation here as we may be called from for an automatic
       generated item, like in natural join.
       Allow reinterpted superset as subset.
+      Use charset narrowing only for equalities, as that would allow
+      to construct ref access.
+      Non-equality comparisons with constants work without charset narrowing,
+      the constant gets converted.
+      Non-equality comparisons with non-constants would need narrowing to
+      enable range optimizer to handle e.g.
+        t1.mb3key_col <= const_table.mb4_col
+      But this doesn't look important.
     */
     bool allow_narrowing= false;
     if (owner->type() == Item::FUNC_ITEM)
@@ -2812,8 +2786,9 @@ Item_func_nullif::fix_length_and_dec(THD *thd)
   fix_char_length(args[2]->max_char_length());
   set_maybe_null();
   m_arg0= args[0];
-  if (setup_args_and_comparator(thd, &cmp))
-    return TRUE;
+  convert_const_compared_to_int_field(thd);
+  if (cmp.set_cmp_func(thd, this, &args[0], &args[1], true/*set_null*/))
+    return true;
   /*
     A special code for EXECUTE..PREPARE.
 
diff --git a/sql/item_cmpfunc.h b/sql/item_cmpfunc.h
index a1de330e97f..9c890d95e8e 100644
--- a/sql/item_cmpfunc.h
+++ b/sql/item_cmpfunc.h
@@ -58,6 +58,7 @@ class Arg_comparator: public Sql_alloc
                                    //   when one of arguments is NULL.
 
   int set_cmp_func(THD *thd, Item_func_or_sum *owner_arg,
+                   const Type_handler *compare_handler,
                    Item **a1, Item **a2);
 
   int compare_not_null_values(longlong val1, longlong val2)
@@ -96,11 +97,24 @@ public:
   bool set_cmp_func_decimal(THD *thd);
 
   inline int set_cmp_func(THD *thd, Item_func_or_sum *owner_arg,
-			  Item **a1, Item **a2, bool set_null_arg)
+                          const Type_handler *compare_handler,
+                          Item **a1, Item **a2, bool set_null_arg)
   {
     set_null= set_null_arg;
-    return set_cmp_func(thd, owner_arg, a1, a2);
+    return set_cmp_func(thd, owner_arg, compare_handler, a1, a2);
   }
+  int set_cmp_func(THD *thd, Item_func_or_sum *owner_arg,
+                   Item **a1, Item **a2, bool set_null_arg)
+  {
+    Item *tmp_args[2]= { *a1, *a2 };
+    Type_handler_hybrid_field_type tmp;
+    if (tmp.aggregate_for_comparison(owner_arg->func_name_cstring(),
+                                     tmp_args, 2, false))
+      return 1;
+    return set_cmp_func(thd, owner_arg, tmp.type_handler(),
+                        a1, a2, set_null_arg);
+  }
+
   inline int compare() { return (this->*func)(); }
 
   int compare_string();		 // compare args[0] & args[1]
@@ -562,9 +576,17 @@ public:
     return this;
   }
   bool fix_length_and_dec(THD *thd) override;
+  bool fix_length_and_dec_generic(THD *thd,
+                                  const Type_handler *compare_handler)
+  {
+    DBUG_ASSERT(args == tmp_arg);
+    return cmp.set_cmp_func(thd, this, compare_handler,
+                            tmp_arg, tmp_arg + 1, true/*set_null*/);
+  }
   int set_cmp_func(THD *thd)
   {
-    return cmp.set_cmp_func(thd, this, tmp_arg, tmp_arg + 1, true);
+    DBUG_ASSERT(args == tmp_arg);
+    return cmp.set_cmp_func(thd, this, tmp_arg, tmp_arg + 1, true/*set_null*/);
   }
   CHARSET_INFO *compare_collation() const override
   { return cmp.compare_collation(); }
diff --git a/sql/item_func.h b/sql/item_func.h
index 9fdb63428c4..f43b03a6323 100644
--- a/sql/item_func.h
+++ b/sql/item_func.h
@@ -389,15 +389,6 @@ public:
     }
   }
   void convert_const_compared_to_int_field(THD *thd);
-  /**
-    Prepare arguments and setup a comparator.
-    Used in Item_func_xxx with two arguments and a comparator,
-    e.g. Item_bool_func2 and Item_func_nullif.
-    args[0] or args[1] can be modified:
-    - converted to character set and collation of the operation
-    - or replaced to an Item_int_with_ref
-  */
-  bool setup_args_and_comparator(THD *thd, Arg_comparator *cmp);
   Item_func *get_item_func() override { return this; }
   bool is_simplified_cond_processor(void *arg) override
   { return const_item() && !val_int(); }
diff --git a/sql/item_sum.cc b/sql/item_sum.cc
index bbd09a59267..ae92f58cd6f 100644
--- a/sql/item_sum.cc
+++ b/sql/item_sum.cc
@@ -1296,9 +1296,14 @@ void Item_sum_min_max::setup_hybrid(THD *thd, Item *item, Item *value_arg)
   /* Don't cache value, as it will change */
   if (!item->const_item())
     arg_cache->set_used_tables(RAND_TABLE_BIT);
+  DBUG_ASSERT(item->type_handler_for_comparison() ==
+              value->type_handler_for_comparison());
+  DBUG_ASSERT(item->type_handler_for_comparison() ==
+              arg_cache->type_handler_for_comparison());
   cmp= new (thd->mem_root) Arg_comparator();
   if (cmp)
-    cmp->set_cmp_func(thd, this, (Item**)&arg_cache, (Item**)&value, FALSE);
+    cmp->set_cmp_func(thd, this, item->type_handler_for_comparison(),
+                      (Item**)&arg_cache, (Item**)&value, FALSE);
   DBUG_VOID_RETURN;
 }
 
diff --git a/sql/sql_acl.cc b/sql/sql_acl.cc
index 0da093cb3ad..b37f6467aeb 100644
--- a/sql/sql_acl.cc
+++ b/sql/sql_acl.cc
@@ -13561,8 +13561,37 @@ static bool find_mpvio_user(MPVIO_EXT *mpvio)
   DBUG_RETURN(0);
 }
 
+
+/**
+  Determine if the client is MySQL Connector/NET.
+
+  Checks whether the given connection attributes blob corresponds to
+  MySQL Connector/NET by examining the "_client_name" attribute, which is
+  expected to be the first attribute in the blob.
+
+  @param connection_attrs - The connection attributes blob.
+  @param length - The length of the blob.
+
+  @return true if the client is MySQL Connector/NET, false otherwise.
+*/
+static inline bool is_connector_net_client(const char *connection_attrs,
+                                           size_t length)
+{
+  constexpr LEX_CSTRING prefix=
+    {STRING_WITH_LEN("\x0c_client_name\x13mysql-connector-net")};
+
+  if (length < prefix.length)
+    return false;
+
+  /* Optimization to avoid following memcmp in common cases.*/
+  if (connection_attrs[prefix.length - 1] != prefix.str[prefix.length - 1])
+    return false;
+
+  return !memcmp(connection_attrs, prefix.str, prefix.length);
+}
+
 static bool
-read_client_connect_attrs(char **ptr, char *end, CHARSET_INFO *from_cs)
+read_client_connect_attrs(char **ptr, char *end, THD* thd)
 {
   ulonglong length;
   char *ptr_save= *ptr;
@@ -13585,10 +13614,14 @@ read_client_connect_attrs(char **ptr, char *end, CHARSET_INFO *from_cs)
   if (length > 65535)
     return true;
 
-  if (PSI_CALL_set_thread_connect_attrs(*ptr, (uint)length, from_cs) &&
+  if (PSI_CALL_set_thread_connect_attrs(*ptr, (uint)length, thd->charset()) &&
       current_thd->variables.log_warnings)
     sql_print_warning("Connection attributes of length %llu were truncated",
                       length);
+
+  /* Connector/Net crashes, when "show collations" returns NULL IDs*/
+  if (is_connector_net_client(*ptr, length))
+    thd->variables.old_behavior |= OLD_MODE_NO_NULL_COLLATION_IDS;
   return false;
 }
 
@@ -13722,7 +13755,7 @@ static bool parse_com_change_user_packet(MPVIO_EXT *mpvio, uint packet_length)
   }
 
   if ((thd->client_capabilities & CLIENT_CONNECT_ATTRS) &&
-      read_client_connect_attrs(&next_field, end, thd->charset()))
+      read_client_connect_attrs(&next_field, end, thd))
   {
     my_message(ER_UNKNOWN_COM_ERROR, ER_THD(thd, ER_UNKNOWN_COM_ERROR),
                MYF(0));
@@ -13972,7 +14005,7 @@ static ulong parse_client_handshake_packet(MPVIO_EXT *mpvio,
 
   if ((thd->client_capabilities & CLIENT_CONNECT_ATTRS) &&
       read_client_connect_attrs(&next_field, ((char *)net->read_pos) + pkt_len,
-                                mpvio->auth_info.thd->charset()))
+                                mpvio->auth_info.thd))
     return packet_error;
 
   /*
diff --git a/sql/sql_class.h b/sql/sql_class.h
index 86b8d91947b..a22638aa29f 100644
--- a/sql/sql_class.h
+++ b/sql/sql_class.h
@@ -200,6 +200,7 @@ enum enum_binlog_row_image {
 #define OLD_MODE_UTF8_IS_UTF8MB3      (1 << 3)
 #define OLD_MODE_IGNORE_INDEX_ONLY_FOR_JOIN          (1 << 4)
 #define OLD_MODE_COMPAT_5_1_CHECKSUM    (1 << 5)
+#define OLD_MODE_NO_NULL_COLLATION_IDS  (1 << 6)
 
 extern char internal_table_name[2];
 extern char empty_c_string[1];
diff --git a/sql/sql_show.cc b/sql/sql_show.cc
index 547f2b423ff..91a1d794d3d 100644
--- a/sql/sql_show.cc
+++ b/sql/sql_show.cc
@@ -6399,7 +6399,8 @@ int fill_schema_collation(THD *thd, TABLE_LIST *tables, COND *cond)
           tmp_cl->get_collation_name(MY_COLLATION_NAME_MODE_CONTEXT);
         LEX_CSTRING full_collation_name=
           tmp_cl->get_collation_name(MY_COLLATION_NAME_MODE_FULL);
-        bool is_context= cmp(context_collation_name, full_collation_name);
+        bool is_context= cmp(context_collation_name, full_collation_name) &&
+            !(thd->variables.old_behavior & OLD_MODE_NO_NULL_COLLATION_IDS);
         /*
           Some collations are applicable to multiple character sets.
           Display them only once, with the short name (without the
diff --git a/sql/sql_type.cc b/sql/sql_type.cc
index 277f495af4a..33c1b48aad9 100644
--- a/sql/sql_type.cc
+++ b/sql/sql_type.cc
@@ -5668,6 +5668,14 @@ Type_handler_string_result::Item_func_hybrid_field_type_get_date(
 
 /***************************************************************************/
 
+bool Type_handler::Item_bool_rowready_func2_fix_length_and_dec(THD *thd,
+                                          Item_bool_rowready_func2 *func) const
+{
+  return func->fix_length_and_dec_generic(thd, this);
+}
+
+/***************************************************************************/
+
 bool Type_handler_numeric::
        Item_func_between_fix_length_and_dec(Item_func_between *func) const
 {
diff --git a/sql/sql_type.h b/sql/sql_type.h
index 35c13a38668..4042976dde2 100644
--- a/sql/sql_type.h
+++ b/sql/sql_type.h
@@ -55,6 +55,7 @@ class Item_hybrid_func;
 class Item_func_min_max;
 class Item_func_hybrid_field_type;
 class Item_bool_func2;
+class Item_bool_rowready_func2;
 class Item_func_between;
 class Item_func_in;
 class Item_func_round;
@@ -4257,6 +4258,8 @@ public:
   }
   virtual bool Item_eq_value(THD *thd, const Type_cmp_attributes *attr,
                              Item *a, Item *b) const= 0;
+  virtual bool Item_bool_rowready_func2_fix_length_and_dec(THD *thd,
+                                          Item_bool_rowready_func2 *func) const;
   virtual bool Item_hybrid_func_fix_attributes(THD *thd,
                                                const LEX_CSTRING &name,
                                                Type_handler_hybrid_field_type *,
diff --git a/sql/sql_type_fixedbin.h b/sql/sql_type_fixedbin.h
index 88c24ba0776..65418c34032 100644
--- a/sql/sql_type_fixedbin.h
+++ b/sql/sql_type_fixedbin.h
@@ -136,6 +136,21 @@ public:
       return Fbt_null(item, false).is_null();
     }
 
+    /*
+      Check at fix_fields() time if any of the items can return a nullable
+      value on conversion to Fbt.
+    */
+    static bool fix_fields_maybe_null_on_conversion_to_fbt(Item **items,
+                                                           uint count)
+    {
+      for (uint i= 0; i < count; i++)
+      {
+        if (Fbt::fix_fields_maybe_null_on_conversion_to_fbt(items[i]))
+          return true;
+      }
+      return false;
+    }
+
   public:
 
     Fbt(Item *item, bool *error, bool warn= true)
@@ -1534,6 +1549,16 @@ public:
     Fbt_null na(a), nb(b);
     return !na.is_null() && !nb.is_null() && !na.cmp(nb);
   }
+  bool Item_bool_rowready_func2_fix_length_and_dec(THD *thd,
+                                 Item_bool_rowready_func2 *func) const override
+  {
+    if (Type_handler::Item_bool_rowready_func2_fix_length_and_dec(thd, func))
+      return true;
+    if (!func->maybe_null() &&
+        Fbt::fix_fields_maybe_null_on_conversion_to_fbt(func->arguments(), 2))
+      func->set_maybe_null();
+    return false;
+  }
   bool Item_hybrid_func_fix_attributes(THD *thd, const LEX_CSTRING &name,
                                        Type_handler_hybrid_field_type *h,
                                        Type_all_attributes *attr,
@@ -1715,6 +1740,9 @@ public:
 
   bool Item_func_between_fix_length_and_dec(Item_func_between *func) const override
   {
+    if (!func->maybe_null() &&
+        Fbt::fix_fields_maybe_null_on_conversion_to_fbt(func->arguments(), 3))
+      func->set_maybe_null();
     return false;
   }
   longlong Item_func_between_val_int(Item_func_between *func) const override
@@ -1737,6 +1765,10 @@ public:
                                                     Item_func_in *func)
                                                     const override
   {
+    if (!func->maybe_null() &&
+        Fbt::fix_fields_maybe_null_on_conversion_to_fbt(func->arguments(),
+                                                        func->argument_count()))
+      func->set_maybe_null();
     if (func->compatible_types_scalar_bisection_possible())
     {
       return func->value_list_convert_const_to_int(thd) ||
diff --git a/sql/sys_vars.cc b/sql/sys_vars.cc
index 992b52a49ce..30313ce5112 100644
--- a/sql/sys_vars.cc
+++ b/sql/sys_vars.cc
@@ -1049,11 +1049,10 @@ static Sys_var_charptr_fscs Sys_datadir(
 static Sys_var_dbug Sys_dbug(
        "debug", "Built-in DBUG debugger", sys_var::SESSION,
        CMD_LINE(OPT_ARG, '#'), DEFAULT(""), NO_MUTEX_GUARD, NOT_IN_BINLOG,
-       ON_CHECK(check_has_super), ON_UPDATE(0),
-       DEPRECATED("'@@debug_dbug'")); // since 5.5.37
+       ON_CHECK(check_has_super));
 
 static Sys_var_dbug Sys_debug_dbug(
-       "debug_dbug", "Built-in DBUG debugger", sys_var::SESSION,
+       "debug_dbug", "Built-in DBUG debugger. Alias for --debug", sys_var::SESSION,
        CMD_LINE(OPT_ARG, '#'), DEFAULT(""), NO_MUTEX_GUARD, NOT_IN_BINLOG,
        ON_CHECK(check_has_super));
 #endif
@@ -3902,6 +3901,7 @@ static const char *old_mode_names[]=
   "UTF8_IS_UTF8MB3",
   "IGNORE_INDEX_ONLY_FOR_JOIN",
   "COMPAT_5_1_CHECKSUM",
+  "NO_NULL_COLLATION_IDS",
   0
 };
 
diff --git a/storage/innobase/btr/btr0btr.cc b/storage/innobase/btr/btr0btr.cc
index 44b3ffd8da7..995ba9dec7d 100644
--- a/storage/innobase/btr/btr0btr.cc
+++ b/storage/innobase/btr/btr0btr.cc
@@ -787,7 +787,8 @@ static rec_offs *btr_page_get_parent(rec_offs *offsets, mem_heap_t *heap,
 /************************************************************//**
 Returns the upper level node pointer to a page. It is assumed that mtr holds
 an x-latch on the tree.
-@return rec_get_offsets() of the node pointer record */
+@return rec_get_offsets() of the node pointer record
+@retval nullptr on corruption */
 static
 rec_offs*
 btr_page_get_father_block(
@@ -2373,6 +2374,11 @@ btr_attach_half_pages(
 		offsets = btr_page_get_father_block(nullptr, heap, mtr,
 						    &cursor);
 
+		if (UNIV_UNLIKELY(!offsets)) {
+			mem_heap_free(heap);
+			return DB_CORRUPTION;
+		}
+
 		/* Replace the address of the old child node (= page) with the
 		address of the new lower half */
 
@@ -3240,6 +3246,14 @@ btr_lift_page_up(
 			offsets = btr_page_get_father_block(offsets, heap,
 							    mtr, &cursor);
 		}
+
+		if (UNIV_UNLIKELY(!offsets)) {
+parent_corrupted:
+			mem_heap_free(heap);
+			*err = DB_CORRUPTION;
+			return nullptr;
+		}
+
 		father_block = btr_cur_get_block(&cursor);
 		father_page_zip = buf_block_get_page_zip(father_block);
 
@@ -3265,6 +3279,10 @@ btr_lift_page_up(
 								    &cursor);
 			}
 
+			if (UNIV_UNLIKELY(!offsets)) {
+				goto parent_corrupted;
+			}
+
 			blocks[n_blocks++] = b = btr_cur_get_block(&cursor);
 		}
 
@@ -3477,6 +3495,10 @@ get_offsets:
 			NULL, heap, mtr, &father_cursor);
 	}
 
+	if (UNIV_UNLIKELY(!offsets)) {
+		goto corrupted;
+	}
+
 	if (adjust) {
 		nth_rec = page_rec_get_n_recs_before(btr_cur_get_rec(cursor));
 		if (UNIV_UNLIKELY(!nth_rec || nth_rec == ULINT_UNDEFINED)) {
diff --git a/storage/innobase/buf/buf0buf.cc b/storage/innobase/buf/buf0buf.cc
index dae0021d22a..bf5bd162081 100644
--- a/storage/innobase/buf/buf0buf.cc
+++ b/storage/innobase/buf/buf0buf.cc
@@ -2414,14 +2414,21 @@ lookup:
 
       if (discard_attempted || !bpage->frame)
       {
-        /* Even when we are holding a hash_lock, it should be
-        acceptable to wait for a page S-latch here, because
-        buf_page_t::read_complete() will not wait for buf_pool.mutex,
-        and because S-latch would not conflict with a U-latch
-        that would be protecting buf_page_t::write_complete(). */
-        bpage->lock.s_lock();
+        const bool got_s_latch= bpage->lock.s_lock_try();
         hash_lock.unlock_shared();
-        break;
+        if (UNIV_LIKELY(got_s_latch))
+          break;
+        /* We may fail to acquire bpage->lock because
+        buf_page_t::read_complete() may be invoking
+        buf_pool_t::corrupted_evict() on this block, which it would
+        hold an exclusive latch on.
+
+        Let us aqcuire and release buf_pool.mutex to ensure that any
+        buf_pool_t::corrupted_evict() will proceed before we reacquire
+        the hash_lock that it could be waiting for. */
+        mysql_mutex_lock(&buf_pool.mutex);
+        mysql_mutex_unlock(&buf_pool.mutex);
+        goto lookup;
       }
 
       hash_lock.unlock_shared();
diff --git a/storage/innobase/dict/dict0dict.cc b/storage/innobase/dict/dict0dict.cc
index 59b218ba29b..8eb1a52ca03 100644
--- a/storage/innobase/dict/dict0dict.cc
+++ b/storage/innobase/dict/dict0dict.cc
@@ -958,11 +958,12 @@ void dict_sys_t::lock_wait(SRW_LOCK_ARGS(const char *file, unsigned line))
   if (latch_ex_wait_start.compare_exchange_strong
       (old, now, std::memory_order_relaxed, std::memory_order_relaxed))
   {
+#ifdef UNIV_DEBUG
+    latch.x_lock(SRW_LOCK_ARGS(file, line));
+#else
     latch.wr_lock(SRW_LOCK_ARGS(file, line));
+#endif
     latch_ex_wait_start.store(0, std::memory_order_relaxed);
-    ut_ad(!latch_readers);
-    ut_ad(!latch_ex);
-    ut_d(latch_ex= pthread_self());
     return;
   }
 
@@ -977,33 +978,39 @@ void dict_sys_t::lock_wait(SRW_LOCK_ARGS(const char *file, unsigned line))
   if (waited > threshold / 4)
     ib::warn() << "A long wait (" << waited
                << " seconds) was observed for dict_sys.latch";
+#ifdef UNIV_DEBUG
+  latch.x_lock(SRW_LOCK_ARGS(file, line));
+#else
   latch.wr_lock(SRW_LOCK_ARGS(file, line));
-  ut_ad(!latch_readers);
-  ut_ad(!latch_ex);
-  ut_d(latch_ex= pthread_self());
+#endif
 }
 
 #ifdef UNIV_PFS_RWLOCK
 ATTRIBUTE_NOINLINE void dict_sys_t::unlock()
 {
-  ut_ad(latch_ex == pthread_self());
-  ut_ad(!latch_readers);
-  ut_d(latch_ex= 0);
+# ifdef UNIV_DEBUG
+  latch.x_unlock();
+# else
   latch.wr_unlock();
+# endif
 }
 
 ATTRIBUTE_NOINLINE void dict_sys_t::freeze(const char *file, unsigned line)
 {
+# ifdef UNIV_DEBUG
+  latch.s_lock(file, line);
+# else
   latch.rd_lock(file, line);
-  ut_ad(!latch_ex);
-  ut_d(latch_readers++);
+# endif
 }
 
 ATTRIBUTE_NOINLINE void dict_sys_t::unfreeze()
 {
-  ut_ad(!latch_ex);
-  ut_ad(latch_readers--);
+# ifdef UNIV_DEBUG
+  latch.s_unlock();
+# else
   latch.rd_unlock();
+# endif
 }
 #endif /* UNIV_PFS_RWLOCK */
 
@@ -4504,7 +4511,11 @@ void dict_sys_t::close()
   temp_id_hash.free();
 
   unlock();
+#ifdef UNIV_DEBUG
+  latch.free();
+#else
   latch.destroy();
+#endif
 
   mysql_mutex_destroy(&dict_foreign_err_mutex);
 
diff --git a/storage/innobase/handler/ha_innodb.cc b/storage/innobase/handler/ha_innodb.cc
index 92cf943a68f..a32782638bc 100644
--- a/storage/innobase/handler/ha_innodb.cc
+++ b/storage/innobase/handler/ha_innodb.cc
@@ -579,7 +579,13 @@ static PSI_rwlock_info all_innodb_rwlocks[] =
 #  ifdef BTR_CUR_HASH_ADAPT
   { &btr_search_latch_key, "btr_search_latch", 0 },
 #  endif
-  { &dict_operation_lock_key, "dict_operation_lock", 0 },
+  { &dict_operation_lock_key, "dict_operation_lock",
+#  ifdef UNIV_DEBUG
+    PSI_RWLOCK_FLAG_SX
+#  else
+    0
+#  endif
+  },
   { &fil_space_latch_key, "fil_space_latch", 0 },
   { &trx_i_s_cache_lock_key, "trx_i_s_cache_lock", 0 },
   { &trx_purge_latch_key, "trx_purge_latch", 0 },
@@ -13449,14 +13455,7 @@ int ha_innobase::delete_table(const char *name)
       /* FOREIGN KEY constraints cannot exist on partitioned tables. */;
 #endif
     else
-    {
-      dict_sys.freeze(SRW_LOCK_CALL);
-      for (const dict_foreign_t* f : table->referenced_set)
-        if (dict_table_t* child= f->foreign_table)
-          if ((err= lock_table_for_trx(child, trx, LOCK_X)) != DB_SUCCESS)
-            break;
-      dict_sys.unfreeze();
-    }
+      err= lock_table_children(table, trx);
   }
 
   dict_table_t *table_stats= nullptr, *index_stats= nullptr;
@@ -13854,14 +13853,7 @@ int ha_innobase::truncate()
   dict_table_t *table_stats = nullptr, *index_stats = nullptr;
   MDL_ticket *mdl_table = nullptr, *mdl_index = nullptr;
 
-  dberr_t error= DB_SUCCESS;
-
-  dict_sys.freeze(SRW_LOCK_CALL);
-  for (const dict_foreign_t *f : ib_table->referenced_set)
-    if (dict_table_t *child= f->foreign_table)
-      if ((error= lock_table_for_trx(child, trx, LOCK_X)) != DB_SUCCESS)
-        break;
-  dict_sys.unfreeze();
+  dberr_t error= lock_table_children(ib_table, trx);
 
   if (error == DB_SUCCESS)
     error= lock_table_for_trx(ib_table, trx, LOCK_X);
@@ -14052,16 +14044,7 @@ ha_innobase::rename_table(
 		/* There is no need to lock any FOREIGN KEY child tables. */
 	} else if (dict_table_t *table = dict_table_open_on_name(
 		    norm_from, false, DICT_ERR_IGNORE_FK_NOKEY)) {
-		dict_sys.freeze(SRW_LOCK_CALL);
-		for (const dict_foreign_t* f : table->referenced_set) {
-			if (dict_table_t* child = f->foreign_table) {
-				error = lock_table_for_trx(child, trx, LOCK_X);
-				if (error != DB_SUCCESS) {
-					break;
-				}
-			}
-		}
-		dict_sys.unfreeze();
+		error = lock_table_children(table, trx);
 		if (error == DB_SUCCESS) {
 			error = lock_table_for_trx(table, trx, LOCK_X);
 		}
@@ -15589,15 +15572,17 @@ ha_innobase::extra(
 {
 	/* Warning: since it is not sure that MariaDB calls external_lock()
 	before calling this function, m_prebuilt->trx can be obsolete! */
-	trx_t* trx = check_trx_exists(ha_thd());
+	trx_t* trx;
 
 	switch (operation) {
 	case HA_EXTRA_FLUSH:
+		(void)check_trx_exists(ha_thd());
 		if (m_prebuilt->blob_heap) {
 			row_mysql_prebuilt_free_blob_heap(m_prebuilt);
 		}
 		break;
 	case HA_EXTRA_RESET_STATE:
+		trx = check_trx_exists(ha_thd());
 		reset_template();
 		trx->duplicates = 0;
 	stmt_boundary:
@@ -15606,18 +15591,23 @@ ha_innobase::extra(
 		trx->bulk_insert = false;
 		break;
 	case HA_EXTRA_NO_KEYREAD:
+		(void)check_trx_exists(ha_thd());
 		m_prebuilt->read_just_key = 0;
 		break;
 	case HA_EXTRA_KEYREAD:
+		(void)check_trx_exists(ha_thd());
 		m_prebuilt->read_just_key = 1;
 		break;
 	case HA_EXTRA_KEYREAD_PRESERVE_FIELDS:
+		(void)check_trx_exists(ha_thd());
 		m_prebuilt->keep_other_fields_on_keyread = 1;
 		break;
 	case HA_EXTRA_INSERT_WITH_UPDATE:
+		trx = check_trx_exists(ha_thd());
 		trx->duplicates |= TRX_DUP_IGNORE;
 		goto stmt_boundary;
 	case HA_EXTRA_NO_IGNORE_DUP_KEY:
+		trx = check_trx_exists(ha_thd());
 		trx->duplicates &= ~TRX_DUP_IGNORE;
 		if (trx->is_bulk_insert()) {
 			/* Allow a subsequent INSERT into an empty table
@@ -15629,9 +15619,11 @@ ha_innobase::extra(
 		}
 		goto stmt_boundary;
 	case HA_EXTRA_WRITE_CAN_REPLACE:
+		trx = check_trx_exists(ha_thd());
 		trx->duplicates |= TRX_DUP_REPLACE;
 		goto stmt_boundary;
 	case HA_EXTRA_WRITE_CANNOT_REPLACE:
+		trx = check_trx_exists(ha_thd());
 		trx->duplicates &= ~TRX_DUP_REPLACE;
 		if (trx->is_bulk_insert()) {
 			/* Allow a subsequent INSERT into an empty table
@@ -15640,6 +15632,7 @@ ha_innobase::extra(
 		}
 		goto stmt_boundary;
 	case HA_EXTRA_BEGIN_ALTER_COPY:
+		trx = check_trx_exists(ha_thd());
 		m_prebuilt->table->skip_alter_undo = 1;
 		if (m_prebuilt->table->is_temporary()
 		    || !m_prebuilt->table->versioned_by_id()) {
@@ -15652,6 +15645,7 @@ ha_innobase::extra(
 			.first->second.set_versioned(0);
 		break;
 	case HA_EXTRA_END_ALTER_COPY:
+		trx = check_trx_exists(ha_thd());
 		m_prebuilt->table->skip_alter_undo = 0;
 		if (!m_prebuilt->table->is_temporary()
 		    && !high_level_read_only) {
diff --git a/storage/innobase/handler/handler0alter.cc b/storage/innobase/handler/handler0alter.cc
index 04c075f3e01..8edfbcd9413 100644
--- a/storage/innobase/handler/handler0alter.cc
+++ b/storage/innobase/handler/handler0alter.cc
@@ -11222,16 +11222,7 @@ ha_innobase::commit_inplace_alter_table(
 			fts_optimize_remove_table(ctx->old_table);
 		}
 
-		dict_sys.freeze(SRW_LOCK_CALL);
-		for (auto f : ctx->old_table->referenced_set) {
-			if (dict_table_t* child = f->foreign_table) {
-				error = lock_table_for_trx(child, trx, LOCK_X);
-				if (error != DB_SUCCESS) {
-					break;
-				}
-			}
-		}
-		dict_sys.unfreeze();
+		error = lock_table_children(ctx->old_table, trx);
 
 		if (ctx->new_table->fts) {
 			ut_ad(!ctx->new_table->fts->add_wq);
diff --git a/storage/innobase/include/dict0dict.h b/storage/innobase/include/dict0dict.h
index 3513f21b5ec..4e04364af10 100644
--- a/storage/innobase/include/dict0dict.h
+++ b/storage/innobase/include/dict0dict.h
@@ -1311,14 +1311,14 @@ class dict_sys_t
   /** The my_hrtime_coarse().val of the oldest lock_wait() start, or 0 */
   std::atomic<ulonglong> latch_ex_wait_start;
 
-  /** the rw-latch protecting the data dictionary cache */
-  alignas(CPU_LEVEL1_DCACHE_LINESIZE) srw_lock latch;
 #ifdef UNIV_DEBUG
-  /** whether latch is being held in exclusive mode (by any thread) */
-  Atomic_relaxed<pthread_t> latch_ex;
-  /** number of S-latch holders */
-  Atomic_counter<uint32_t> latch_readers;
+  typedef index_lock dict_lock;
+#else
+  typedef srw_lock dict_lock;
 #endif
+
+  /** the rw-latch protecting the data dictionary cache */
+  alignas(CPU_LEVEL1_DCACHE_LINESIZE) dict_lock latch;
 public:
   /** Indexes of SYS_TABLE[] */
   enum
@@ -1469,15 +1469,12 @@ public:
   }
 
 #ifdef UNIV_DEBUG
-  /** @return whether any thread (not necessarily the current thread)
-  is holding the latch; that is, this check may return false
-  positives */
-  bool frozen() const { return latch_readers || latch_ex; }
-  /** @return whether any thread (not necessarily the current thread)
-  is holding a shared latch */
-  bool frozen_not_locked() const { return latch_readers; }
+  /** @return whether the current thread is holding the latch */
+  bool frozen() const { return latch.have_any(); }
+  /** @return whether the current thread is holding a shared latch */
+  bool frozen_not_locked() const { return latch.have_s(); }
   /** @return whether the current thread holds the exclusive latch */
-  bool locked() const { return latch_ex == pthread_self(); }
+  bool locked() const { return latch.have_x(); }
 #endif
 private:
   /** Acquire the exclusive latch */
@@ -1492,13 +1489,11 @@ public:
   /** Exclusively lock the dictionary cache. */
   void lock(SRW_LOCK_ARGS(const char *file, unsigned line))
   {
-    if (latch.wr_lock_try())
-    {
-      ut_ad(!latch_readers);
-      ut_ad(!latch_ex);
-      ut_d(latch_ex= pthread_self());
-    }
-    else
+#ifdef UNIV_DEBUG
+    if (!latch.x_lock_try())
+#else
+    if (!latch.wr_lock_try())
+#endif
       lock_wait(SRW_LOCK_ARGS(file, line));
   }
 
@@ -1513,24 +1508,29 @@ public:
   /** Unlock the data dictionary cache. */
   void unlock()
   {
-    ut_ad(latch_ex == pthread_self());
-    ut_ad(!latch_readers);
-    ut_d(latch_ex= 0);
+# ifdef UNIV_DEBUG
+    latch.x_unlock();
+# else
     latch.wr_unlock();
+# endif
   }
   /** Acquire a shared lock on the dictionary cache. */
   void freeze()
   {
+# ifdef UNIV_DEBUG
+    latch.s_lock();
+# else
     latch.rd_lock();
-    ut_ad(!latch_ex);
-    ut_d(latch_readers++);
+# endif
   }
   /** Release a shared lock on the dictionary cache. */
   void unfreeze()
   {
-    ut_ad(!latch_ex);
-    ut_ad(latch_readers--);
+# ifdef UNIV_DEBUG
+    latch.s_unlock();
+# else
     latch.rd_unlock();
+# endif
   }
 #endif
 
diff --git a/storage/innobase/include/lock0lock.h b/storage/innobase/include/lock0lock.h
index eca8c2cb614..8f0da1695ad 100644
--- a/storage/innobase/include/lock0lock.h
+++ b/storage/innobase/include/lock0lock.h
@@ -431,6 +431,13 @@ dberr_t lock_table_for_trx(dict_table_t *table, trx_t *trx, lock_mode mode,
                            bool no_wait= false)
 	MY_ATTRIBUTE((nonnull, warn_unused_result));
 
+/** Lock the child tables of a table.
+@param table    parent table
+@param trx      transaction
+@return error code */
+dberr_t lock_table_children(dict_table_t *table, trx_t *trx)
+	MY_ATTRIBUTE((nonnull, warn_unused_result));
+
 /** Exclusively lock the data dictionary tables.
 @param trx  dictionary transaction
 @return error code
diff --git a/storage/innobase/lock/lock0lock.cc b/storage/innobase/lock/lock0lock.cc
index 101735b5d6a..0f2d5380935 100644
--- a/storage/innobase/lock/lock0lock.cc
+++ b/storage/innobase/lock/lock0lock.cc
@@ -3940,6 +3940,8 @@ static void lock_table_dequeue(lock_t *in_lock, bool owns_wait_mutex)
 dberr_t lock_table_for_trx(dict_table_t *table, trx_t *trx, lock_mode mode,
                            bool no_wait)
 {
+  ut_ad(!dict_sys.frozen());
+
   mem_heap_t *heap= mem_heap_create(512);
   sel_node_t *node= sel_node_create(heap);
   que_thr_t *thr= pars_complete_graph_for_exec(node, trx, heap, nullptr);
@@ -3976,6 +3978,36 @@ run_again:
   return err;
 }
 
+/** Lock the child tables of a table.
+@param table    parent table
+@param trx      transaction
+@return error code */
+dberr_t lock_table_children(dict_table_t *table, trx_t *trx)
+{
+  dict_sys.freeze(SRW_LOCK_CALL);
+  std::vector<dict_table_t*> children;
+
+  for (auto f : table->referenced_set)
+    if (dict_table_t *child= f->foreign_table)
+    {
+      child->acquire();
+      children.emplace_back(child);
+    }
+  dict_sys.unfreeze();
+
+  dberr_t err= DB_SUCCESS;
+
+  for (auto child : children)
+    if ((err= lock_table_for_trx(child, trx, LOCK_X)) != DB_SUCCESS)
+      break;
+
+  for (auto child : children)
+    child->release();
+
+  return err;
+}
+
+
 /** Exclusively lock the data dictionary tables.
 @param trx  dictionary transaction
 @return error code