MySQL raises ER_UNSUPPORTED_BY_REPLICATION_THREAD when a replica thread executes a statement that replicas are not allowed to run.
MySQL error 3063 ER_UNSUPPORTED_BY_REPLICATION_THREAD occurs when a replica executes a forbidden statement like FLUSH or SET GLOBAL, stopping replication. Remove, skip, or filter the statement to resume replication.
ER_UNSUPPORTED_BY_REPLICATION_THREAD
MySQL raises error 3063 with message 'Cannot %s from a replication slave thread' when the replica SQL or IO thread attempts to execute a statement that is forbidden inside the replication context.
The problem appears from MySQL 5.7.5 onward because the server tightens safety checks. When the error fires replication halts, causing delay between source and replica and risking stale reads and data inconsistency.
Replication threads have limited privileges. Statements that alter server level state such as FLUSH TABLES, RESET MASTER, INSTALL PLUGIN, SET GLOBAL and CLONE are blocked. If those commands are recorded in the binary log the replica tries to run them and fails with error 3063.
The error also occurs when stored procedures or triggers include disallowed statements and are invoked during replication. Upgraded versions can surface the problem because syntax that was silently ignored in older releases is now actively rejected.
Identify the exact SQL that triggered the stop by inspecting SHOW SLAVE STATUS and the Last_SQL_Error field. The relay log coordinates reveal the failing event.
Skip or rewrite the offending statement. For a one off situation run SET GLOBAL sql_slave_skip_counter = 1 then START SLAVE to resume replication, but be sure the operation is idempotent to avoid data drift. Prefer removing the statement on the source.
When possible convert the operation into a replica safe equivalent. Run FLUSH TABLES or server variable changes only on the primary, or wrap them in IF logic that checks @@super_read_only so they never execute on a replica.
Backup scripts sometimes log RESET MASTER which breaks replicas. Remove RESET MASTER or run it with LOG_SLAVE_UPDATES disabled so the statement is not written to the binary log.
Online schema change tools may issue ALTER USER or SET PASSWORD commands. Upgrade the tool or configure it to skip privileged statements during migration in order to keep replication healthy.
Installing plugins with INSTALL PLUGIN on the primary logs the action. Instead manually install the plugin on each replica and then skip the original binary log event to keep metadata in sync.
Enable super_read_only on replicas so accidental interactive commands cannot be issued and later logged.
Use binary log filters like binlog_ignore_db or replicate_ignore_table to exclude maintenance schemas that generate unsafe statements.
Adopt MySQL 8 channel based replication and send maintenance events through a channel that replicas are not subscribed to, preventing exposure to blocked statements.
Galaxy's context aware SQL editor lets teams review and endorse production scripts in a shared workspace, reducing the chance of unsafe statements reaching the binary log.
Error 1792 ER_BINLOG_FORMAT_MIXED occurs when the binlog format conflicts with the statement. Switching to ROW format or avoiding unsafe statements resolves it.
Error 1236 ER_MASTER_FATAL_ERROR_READING_BINLOG means the replica cannot read the source binary log. Reprovision the replica or restore from a fresh backup.
Error 1594 ER_SLAVE_UNEXPECTED_MASTER_FAILOVER signals an unexpected master change. Update the connection parameters with CHANGE MASTER TO and restart replication.
Maintenance statements like FLUSH TABLES or RESET MASTER are logged on the primary but forbidden on replicas, immediately triggering error 3063.
SET GLOBAL or other server variable adjustments propagate through the binary log and fail on replicas because they require SUPER privileges not granted to replication threads.
INSTALL PLUGIN and CLONE statements change server binaries or data directories, both blocked for safety inside a replication thread.
Stored procedures or triggers that embed FLUSH or RESET commands execute automatically during replication and cause the replica to stop.
Arises when binlog format mixed conflicts with statement type. Change to ROW format.
Replica cannot read the binary log from the source due to corruption or log rotation.
Indicates the replica detected a master failover without proper reconfiguration.
No, it only stops the replica thread. The primary continues to operate normally.
Only if the statement is not required for data consistency. Always verify before skipping.
Read Last_SQL_Error and the relay log position shown by SHOW SLAVE STATUS to locate the event.
Yes. Galaxy's shared editor and endorsement workflow let teams review maintenance scripts, reducing the chance unsafe commands reach production.
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