diff -ruN mysql-9.7.0/sql/item_sum.cc mysql-9.7.0.patched/sql/item_sum.cc
--- mysql-9.7.0/sql/item_sum.cc	2026-04-07 16:08:28.000000000 +0000
+++ mysql-9.7.0.patched/sql/item_sum.cc	2026-04-28 08:44:36.083552761 +0000
@@ -4368,9 +4368,13 @@
         result->length(), &well_formed_error);
     result->length(old_length + add_length);
     item->warning_for_row = true;
-    push_warning_printf(
-        current_thd, Sql_condition::SL_WARNING, ER_CUT_VALUE_GROUP_CONCAT,
-        ER_THD(current_thd, ER_CUT_VALUE_GROUP_CONCAT), item->row_count);
+
+    if (current_thd->variables.strict_group_concat)
+      my_error(ER_CUT_VALUE_GROUP_CONCAT, MYF(0), item->row_count);
+    else
+      push_warning_printf(
+          current_thd, Sql_condition::SL_WARNING, ER_CUT_VALUE_GROUP_CONCAT,
+          ER_THD(current_thd, ER_CUT_VALUE_GROUP_CONCAT), item->row_count);
 
     /**
        To avoid duplicated warnings in Item_func_group_concat::val_str()
@@ -4863,9 +4867,13 @@
   if (table && table->blob_storage &&
       table->blob_storage->is_truncated_value()) {
     warning_for_row = true;
-    push_warning_printf(
-        current_thd, Sql_condition::SL_WARNING, ER_CUT_VALUE_GROUP_CONCAT,
-        ER_THD(current_thd, ER_CUT_VALUE_GROUP_CONCAT), row_count);
+
+    if (current_thd->variables.strict_group_concat)
+      my_error(ER_CUT_VALUE_GROUP_CONCAT, MYF(0), row_count);
+    else
+      push_warning_printf(
+          current_thd, Sql_condition::SL_WARNING, ER_CUT_VALUE_GROUP_CONCAT,
+          ER_THD(current_thd, ER_CUT_VALUE_GROUP_CONCAT), row_count);
   }
 
   return &result;
diff -ruN mysql-9.7.0/sql/sys_vars.cc mysql-9.7.0.patched/sql/sys_vars.cc
--- mysql-9.7.0/sql/sys_vars.cc	2026-04-07 16:08:28.000000000 +0000
+++ mysql-9.7.0.patched/sql/sys_vars.cc	2026-04-28 08:07:13.948369433 +0000
@@ -5699,6 +5699,12 @@
     HINT_UPDATEABLE SESSION_VAR(group_concat_max_len), CMD_LINE(REQUIRED_ARG),
     VALID_RANGE(4, ULONG_MAX), DEFAULT(1024), BLOCK_SIZE(1));
 
+static Sys_var_bool Sys_strict_group_concat(
+    "strict_group_concat",
+    "When GROUP_CONCAT function handle exceeds group_concat_max_len, "
+    "make an error instead of a warning.",
+    HINT_UPDATEABLE SESSION_VAR(strict_group_concat), CMD_LINE(OPT_ARG), DEFAULT(false));
+
 static char *glob_hostname_ptr;
 static Sys_var_charptr Sys_hostname(
     "hostname", "Server host name",
diff -ruN mysql-9.7.0/sql/system_variables.h mysql-9.7.0.patched/sql/system_variables.h
--- mysql-9.7.0/sql/system_variables.h	2026-04-07 16:08:28.000000000 +0000
+++ mysql-9.7.0.patched/sql/system_variables.h	2026-04-28 07:21:41.723981542 +0000
@@ -274,6 +274,7 @@
   ulong trans_alloc_block_size;
   ulong trans_prealloc_size;
   ulong group_concat_max_len;
+  bool strict_group_concat;
   ulong binlog_format;  ///< binlog format for this thd (see enum_binlog_format)
   ulong rbr_exec_mode_options;  // see enum_rbr_exec_mode
   bool binlog_direct_non_trans_update;