<p>The slave SQL thread reports that a command sent to the master failed, halting replication.</p>
<p>MySQL Error 1597 ER_SLAVE_MASTER_COM_FAILURE arises when a replication slave cannot execute a command returned by the master. Inspect the master's error log, correct the failing statement or privileges, and restart the slave to resume replication.</p>
Master command %s failed: %s
The error message Master command %s failed: %s means the replication slave asked the master to run a command, but the master returned an error string instead of OK. The slave records error 1597 and stops the SQL thread.
Because the SQL thread is stopped, the slave no longer applies relay log events, causing replication lag or total breakage until the issue is fixed.
The issue surfaces during normal asynchronous replication, when the slave executes CHANGE MASTER, START SLAVE, or any statement that requires interaction with the master. It is common after privilege changes, schema alterations, or network interruptions.
Replication delay reduces data freshness for reads and breaks high availability setups. Unfixed, it can cause data divergence if writes continue on the master while the slave is stalled.
A DDL or DML statement that fails on the master echoes an error back to the slave, triggering 1597.
The replication user lacks SUPER, RELOAD, or other required privileges to issue commands like FLUSH TABLES, resulting in failure.
The master supports commands unknown to the older slave or vice versa, causing command rejection.
A lost TCP packet or timeout corrupts the in-flight command, and the master returns an error on re-send.
Indicates the slave I/O or SQL thread unexpectedly stopped for a general reason.
Shows that the slave could not read the master's binary log, often due to log rotation or corruption.
Occurs when MASTER_DELAY is set but the SQL thread is not running, blocking replication.
Only the SQL thread stops. The I/O thread usually keeps fetching relay logs, increasing relay log position but not applying events.
You can skip the event if it is harmless, but confirm with the application team to avoid data loss or inconsistency.
A restart alone does not solve the underlying issue. You must address the failing command or missing privileges first.
Galaxy's query history and collaboration features let teams audit recent DDL, quickly locate the offending statement, and share the fix across environments.
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