diff --git a/client/mysqltest.cc b/client/mysqltest.cc
index 4c944fd0f1b..1b64e3d2db1 100644
--- a/client/mysqltest.cc
+++ b/client/mysqltest.cc
@@ -5922,14 +5922,20 @@ int connect_n_handle_errors(struct st_command *command,
       stay clear of trying to work out which exact user-limit was
       exceeded.
     */
+    auto my_err= mysql_errno(con);
+    if(my_err == 0)
+    {
+      /* Workaround client library bug, not indicating connection error. */
+      my_err= CR_SERVER_LOST;
+    }
 
-    if (((mysql_errno(con) == ER_TOO_MANY_USER_CONNECTIONS) ||
-         (mysql_errno(con) == ER_USER_LIMIT_REACHED)) &&
+    if (((my_err == ER_TOO_MANY_USER_CONNECTIONS) ||
+         (my_err == ER_USER_LIMIT_REACHED)) &&
         (failed_attempts++ < opt_max_connect_retries))
     {
       int i;
 
-      i= match_expected_error(command, mysql_errno(con), mysql_sqlstate(con));
+      i= match_expected_error(command, my_err, mysql_sqlstate(con));
 
       if (i >= 0)
         goto do_handle_error;                 /* expected error, handle */
@@ -5939,9 +5945,9 @@ int connect_n_handle_errors(struct st_command *command,
     }
 
 do_handle_error:
-    var_set_errno(mysql_errno(con));
-    handle_error(command, mysql_errno(con), mysql_error(con),
-		 mysql_sqlstate(con), ds);
+    var_set_errno(my_err);
+    handle_error(command, my_err, mysql_error(con),
+                 mysql_sqlstate(con), ds);
     return 0; /* Not connected */
   }
 
diff --git a/mysql-test/lib/mtr_cases.pm b/mysql-test/lib/mtr_cases.pm
index c72717578cb..d9ab10b60f6 100644
--- a/mysql-test/lib/mtr_cases.pm
+++ b/mysql-test/lib/mtr_cases.pm
@@ -398,7 +398,8 @@ sub collect_suite_name($$)
     {
       my @dirs = my_find_dir(dirname($::glob_mysql_test_dir),
                              ["mysql-test/suite", @plugin_suitedirs ],
-                             $suitename);
+                             $suitename,
+                             $::opt_skip_not_found ? NOT_REQUIRED : undef);
       #
       # if $suitename contained wildcards, we'll have many suites and
       # their overlays here. Let's group them appropriately.
diff --git a/mysql-test/main/func_json.test b/mysql-test/main/func_json.test
index 41b827a02dc..dcbbd6055b1 100644
--- a/mysql-test/main/func_json.test
+++ b/mysql-test/main/func_json.test
@@ -1158,7 +1158,9 @@ SELECT JSON_REMOVE('{"A": { "B": 1 }}', '$.A.B.C.D');
 SET @save_collation_connection= @@collation_connection;
 
 SET collation_connection='utf16_bin';
+--disable_service_connection
 SELECT JSON_EXTRACT('{"a": 1,"b": 2}','$.a');
+--enable_service_connection
 
 SET @@collation_connection= @save_collation_connection;
 
diff --git a/sql/mysqld.cc b/sql/mysqld.cc
index a66f62aa16a..4d66b3f18b2 100644
--- a/sql/mysqld.cc
+++ b/sql/mysqld.cc
@@ -3108,6 +3108,15 @@ static void start_signal_handler(void)
   DBUG_VOID_RETURN;
 }
 
+/** Called only from signal_hand function. */
+static void* exit_signal_handler()
+{
+    my_thread_end();
+    signal_thread_in_use= 0;
+    pthread_exit(0);  // Safety
+    return nullptr;  // Avoid compiler warnings
+}
+
 
 /** This threads handles all signals and alarms. */
 /* ARGSUSED */
@@ -3168,10 +3177,7 @@ pthread_handler_t signal_hand(void *arg __attribute__((unused)))
     if (abort_loop)
     {
       DBUG_PRINT("quit",("signal_handler: calling my_thread_end()"));
-      my_thread_end();
-      signal_thread_in_use= 0;
-      pthread_exit(0);				// Safety
-      return 0;                                 // Avoid compiler warnings
+      return exit_signal_handler();
     }
     switch (sig) {
     case SIGTERM:
@@ -3190,6 +3196,7 @@ pthread_handler_t signal_hand(void *arg __attribute__((unused)))
         PSI_CALL_delete_current_thread();
         my_sigset(sig, SIG_IGN);
         break_connect_loop(); // MIT THREAD has a alarm thread
+        return exit_signal_handler();
       }
       break;
     case SIGHUP:
diff --git a/storage/spider/mysql-test/spider/bugfix/r/mdev_34002.result b/storage/spider/mysql-test/spider/bugfix/r/mdev_34002.result
new file mode 100644
index 00000000000..7e266156e0a
--- /dev/null
+++ b/storage/spider/mysql-test/spider/bugfix/r/mdev_34002.result
@@ -0,0 +1,9 @@
+INSTALL PLUGIN Spider SONAME 'ha_spider.so';
+CREATE TABLE t (c DATE, c2 VARCHAR(1025) CHARACTER SET utf8mb3, UNIQUE KEY k(c2)) ENGINE=SPIDER;
+UPDATE t SET c='２';
+ERROR HY000: Unable to connect to foreign data source: localhost
+drop table t;
+Warnings:
+Warning	1620	Plugin is busy and will be uninstalled on shutdown
+Note	1305	PLUGIN SPIDER_ALLOC_MEM does not exist
+Note	1305	PLUGIN SPIDER_WRAPPER_PROTOCOLS does not exist
diff --git a/storage/spider/mysql-test/spider/bugfix/t/mdev_34002.test b/storage/spider/mysql-test/spider/bugfix/t/mdev_34002.test
new file mode 100644
index 00000000000..575a306589d
--- /dev/null
+++ b/storage/spider/mysql-test/spider/bugfix/t/mdev_34002.test
@@ -0,0 +1,7 @@
+INSTALL PLUGIN Spider SONAME 'ha_spider.so';
+CREATE TABLE t (c DATE, c2 VARCHAR(1025) CHARACTER SET utf8mb3, UNIQUE KEY k(c2)) ENGINE=SPIDER;
+--error ER_CONNECT_TO_FOREIGN_DATA_SOURCE
+UPDATE t SET c='２';
+drop table t;
+--disable_query_log
+--source ../../include/clean_up_spider.inc
diff --git a/storage/spider/spd_db_include.h b/storage/spider/spd_db_include.h
index e1afaafc4a7..77cc9b7523c 100644
--- a/storage/spider/spd_db_include.h
+++ b/storage/spider/spd_db_include.h
@@ -1134,11 +1134,8 @@ public:
   ha_spider *spider;
   spider_db_share *db_share;
   int first_link_idx;
-#ifdef SPIDER_HAS_GROUP_BY_HANDLER
-  SPIDER_LINK_IDX_CHAIN *link_idx_chain;
-#endif
-  bool strict_group_by;
-  bool no_where_cond;
+  bool strict_group_by= false;
+  bool no_where_cond= false;
   spider_db_handler(ha_spider *spider, spider_db_share *db_share) :
     dbton_id(db_share->dbton_id), spider(spider), db_share(db_share),
     first_link_idx(-1) {}