MySQL throws ER_SLAVE_CHANNEL_NOT_RUNNING (3082) when you issue a replication statement against a channel whose replication threads are not running.
ER_SLAVE_CHANNEL_NOT_RUNNING (3082) appears in MySQL when a replication operation is executed on a channel with stopped I/O or SQL threads. Start the channel with START SLAVE FOR CHANNEL 'channel_name' or restart replication to resolve the error.
ER_SLAVE_CHANNEL_NOT_RUNNING
MySQL returns ER_SLAVE_CHANNEL_NOT_RUNNING with SQL state HY000 when a replication statement needs active replication threads but the selected channel's threads are stopped.
The error was introduced in MySQL 5.7.6 and appears with multi-source replication or when named channels are used.
It typically surfaces during CHANGE MASTER, STOP SLAVE, START SLAVE UNTIL, RESET SLAVE, or replication filtering commands issued against a channel whose I/O or SQL thread is not running.
Administrators updating replication settings without first starting the channel encounter the message immediately.
A stopped replication channel means data lag, missing writes, and potential inconsistency between master and replica. Production read scaling and disaster-recovery strategies depend on continuous replication.
Ignoring the error leaves replicas stale and degrades application performance that relies on up-to-date data.
The primary trigger is executing replication management statements on a channel that is not running. MySQL blocks the operation to protect metadata integrity.
Administrative shutdowns, crashes, network failures, or configuration edits often stop replication threads and create the precondition for the error.
Start the affected channel with START SLAVE FOR CHANNEL 'channel_name'. Verify that both I/O and SQL threads change to the Running state in SHOW SLAVE STATUS.
If the channel fails to start, inspect error logs for connectivity issues, credential problems, or binary log gaps, and resolve them before retrying.
During delayed replication maintenance, DBAs sometimes forget to restart the channel after modifications. A simple START SLAVE resolves the error.
After a server restart, channels configured to start manually remain stopped. Automate startup or run START SLAVE in an init script to prevent the error.
Automate replication monitoring with tools such as pt-heartbeat, MySQL Shell, or Galaxy alerts so stopped threads are detected within seconds.
Document standard operating procedures that always include a START SLAVE check after configuration changes.
ER_SLAVE_IO_RUNNING and ER_SLAVE_SQL_RUNNING indicate thread states and usually accompany replication delays. They differ by reporting thread status rather than blocking commands. Restart the respective thread or fix connectivity to resolve them.
ER_MTS_CANT_PARSED_ERROR_LOG means parallel replication encountered an unparseable event; inspect relay logs, then restart replication.
Administrators stop replication for schema changes but forget START SLAVE FOR CHANNEL 'name'.
Configuring replication channels with MANUAL_START leaves them stopped after reboot, producing the error on management commands.
I/O thread disconnects due to network issues, stops, and later commands fail with ER_SLAVE_CHANNEL_NOT_RUNNING.
Indicates the I/O thread died unexpectedly. Investigate network or authentication issues.
The SQL thread stopped due to an error in the relay log. Check SHOW SLAVE STATUS Last_SQL_Error and fix the event.
Parallel replication cannot apply a large event. Increase slave_pending_jobs_size_max or disable MTS.
Authentication mismatch, missing binary logs, or permissions can prevent the channel from starting. Review the error log and ensure MASTER_HOST, USER, and LOG_FILE are correct.
If the channel is obsolete, run STOP SLAVE FOR CHANNEL 'name', RESET SLAVE ALL FOR CHANNEL 'name', and remove its configuration to avoid repeated errors.
Use performance_schema.replication_connection_status, pt-heartbeat, or Galaxy alert rules to watch thread states and replication lag.
Galaxy's query history and alerting surface replication state metrics so engineers can detect and start stopped channels directly from the editor.
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