diff --git a/mysql-test/main/partition_debug_sync.result b/mysql-test/main/partition_debug_sync.result
index 7006491fcaa..635f7735e6c 100644
--- a/mysql-test/main/partition_debug_sync.result
+++ b/mysql-test/main/partition_debug_sync.result
@@ -53,9 +53,14 @@ SET DEBUG_SYNC= 'alter_table_before_rename_result_table WAIT_FOR delete_done';
 ALTER TABLE t2 REMOVE PARTITIONING;
 connection default;
 SET DEBUG_SYNC= 'now WAIT_FOR removing_partitions';
-SET DEBUG_SYNC= 'rm_table_no_locks_before_delete_table SIGNAL waiting_for_alter';
+SET DEBUG_SYNC= 'rm_table_no_locks_before_delete_table SIGNAL waiting_for_alter WAIT_FOR mtr_continue';
 SET DEBUG_SYNC= 'rm_table_no_locks_before_binlog SIGNAL delete_done';
 DROP TABLE IF EXISTS t2;
+# Create a new connection thread to orchestrate the ALTER and DROP
+# threads' DEBUG_SYNC points to avoid lost signals
+connect con2,localhost,root,,;
+SET DEBUG_SYNC= 'now SIGNAL mtr_continue';
+connection default;
 connection con1;
 ERROR 42S02: Table 'test.t2' doesn't exist
 SET DEBUG_SYNC= 'RESET';
diff --git a/mysql-test/main/partition_debug_sync.test b/mysql-test/main/partition_debug_sync.test
index 09ebba0b0e2..bc49153f803 100644
--- a/mysql-test/main/partition_debug_sync.test
+++ b/mysql-test/main/partition_debug_sync.test
@@ -66,12 +66,27 @@ SET DEBUG_SYNC= 'alter_table_before_rename_result_table WAIT_FOR delete_done';
 --send ALTER TABLE t2 REMOVE PARTITIONING
 connection default;
 SET DEBUG_SYNC= 'now WAIT_FOR removing_partitions';
-SET DEBUG_SYNC= 'rm_table_no_locks_before_delete_table SIGNAL waiting_for_alter';
+
+SET DEBUG_SYNC= 'rm_table_no_locks_before_delete_table SIGNAL waiting_for_alter WAIT_FOR mtr_continue';
 SET DEBUG_SYNC= 'rm_table_no_locks_before_binlog SIGNAL delete_done';
-DROP TABLE IF EXISTS t2;
+--send DROP TABLE IF EXISTS t2
+
+--echo # Create a new connection thread to orchestrate the ALTER and DROP
+--echo # threads' DEBUG_SYNC points to avoid lost signals
+connect(con2,localhost,root,,);
+let $wait_condition= select count(*)=0 from information_schema.processlist where state like "debug sync point: alter_table_before_open_tables";
+source include/wait_condition.inc;
+SET DEBUG_SYNC= 'now SIGNAL mtr_continue';
+
+# Return execution for DROP TABLE
+connection default;
+--reap
+
+# Return execution for ALTER TABLE
 connection con1;
 --error ER_NO_SUCH_TABLE
 --reap
+
 SET DEBUG_SYNC= 'RESET';
 disconnect con1;
 --source include/wait_until_disconnected.inc
diff --git a/mysql-test/main/query_cache_debug.test b/mysql-test/main/query_cache_debug.test
index 90b76077cac..af82927245b 100644
--- a/mysql-test/main/query_cache_debug.test
+++ b/mysql-test/main/query_cache_debug.test
@@ -197,8 +197,17 @@ SET DEBUG_SYNC="now WAIT_FOR parked1_2";
 --echo ** and finally release the mutex. The threads will continue to wait
 --echo ** until a broadcast signal reaches them causing both threads to 
 --echo ** come alive and check the condition.
+
+# Before sending signals back-to-back, we have to ensure the previous signal
+# was received
+let $wait_condition= select count(*)=3 from information_schema.processlist where state like "%debug%";
+source include/wait_condition.inc;
 SET DEBUG_SYNC="now SIGNAL go2";
+let $wait_condition= select count(*)=2 from information_schema.processlist where state like "%debug%";
+source include/wait_condition.inc;
 SET DEBUG_SYNC="now SIGNAL go3";
+let $wait_condition= select count(*)=1 from information_schema.processlist where state like "%debug%";
+source include/wait_condition.inc;
 
 --echo **
 --echo ** Finally signal the DELETE statement on THD1 one last time.
@@ -208,6 +217,8 @@ SET DEBUG_SYNC="now SIGNAL go3";
 --echo ** invalidations and a broadcast signal will be sent to the thread 
 --echo ** group holding result set writers.
 SET DEBUG_SYNC="now SIGNAL go1_2";
+let $wait_condition= select count(*)=0 from information_schema.processlist where state like "%debug%";
+source include/wait_condition.inc;
 
 --echo **
 --echo *************************************************************************
diff --git a/mysql-test/suite/rpl/t/rpl_dump_request_retry_warning.test b/mysql-test/suite/rpl/t/rpl_dump_request_retry_warning.test
index d750d44ae71..1ee043623ae 100644
--- a/mysql-test/suite/rpl/t/rpl_dump_request_retry_warning.test
+++ b/mysql-test/suite/rpl/t/rpl_dump_request_retry_warning.test
@@ -43,6 +43,12 @@ START SLAVE;
 SET DEBUG_SYNC= 'now WAIT_FOR parked';
 SET @@GLOBAL.debug_dbug = @saved_dbug;
 SET DEBUG_SYNC= 'now SIGNAL continue';
+
+# Ensure the last DEBUG_SYNC signal was received by the target thread before
+# reset; otherwise, the reset can drop the last signal before it gets
+# acknowledged
+let $wait_condition= select count(*)=0 from information_schema.processlist where state like "%debug%";
+source include/wait_condition.inc;
 SET DEBUG_SYNC= 'RESET';
 
 --source include/wait_for_slave_io_to_start.inc
diff --git a/storage/innobase/trx/trx0undo.cc b/storage/innobase/trx/trx0undo.cc
index 3d2d9752a42..207e7e83415 100644
--- a/storage/innobase/trx/trx0undo.cc
+++ b/storage/innobase/trx/trx0undo.cc
@@ -1,7 +1,7 @@
 /*****************************************************************************
 
 Copyright (c) 1996, 2016, Oracle and/or its affiliates. All Rights Reserved.
-Copyright (c) 2014, 2021, MariaDB Corporation.
+Copyright (c) 2014, 2022, MariaDB Corporation.
 
 This program is free software; you can redistribute it and/or modify it under
 the terms of the GNU General Public License as published by the Free Software
@@ -466,6 +466,10 @@ static uint16_t trx_undo_header_create(buf_block_t *undo_page, trx_id_t trx_id,
                   free);
   mtr->write<8,mtr_t::MAYBE_NOP>(*undo_page, free + TRX_UNDO_TRX_ID +
                                  undo_page->frame, trx_id);
+  if (UNIV_UNLIKELY(mach_read_from_8(free + TRX_UNDO_TRX_NO +
+                                     undo_page->frame)))
+    mtr->memset(undo_page, free + TRX_UNDO_TRX_NO, 8, 0);
+
   /* Write TRX_UNDO_NEEDS_PURGE=1 and TRX_UNDO_LOG_START. */
   mach_write_to_2(buf, 1);
   memcpy_aligned<2>(buf + 2, start, 2);
@@ -886,12 +890,19 @@ corrupted:
 		sql_print_error("InnoDB: unsupported undo header state %u",
 				state);
 		goto corrupted;
+	case TRX_UNDO_CACHED:
+		if (UNIV_UNLIKELY(type != 0)) {
+			/* This undo page was not updated by MariaDB
+			10.3 or later. The TRX_UNDO_TRX_NO field may
+			contain garbage. */
+			break;
+		}
+		goto read_trx_no;
 	case TRX_UNDO_TO_PURGE:
 		if (UNIV_UNLIKELY(type == 1)) {
 			goto corrupted_type;
 		}
-		/* fall through */
-	case TRX_UNDO_CACHED:
+	read_trx_no:
 		trx_id_t id = mach_read_from_8(TRX_UNDO_TRX_NO + undo_header);
 		if (id >> 48) {
 			sql_print_error("InnoDB: corrupted TRX_NO %llx", id);