<p>MySQL Error 1593 (ER_SLAVE_FATAL_ERROR) signals that the replica SQL thread hit a fatal condition and stopped processing relay log events.</p>
<p>MySQL Error 1593: ER_SLAVE_FATAL_ERROR occurs when the replica's SQL thread encounters a non-recoverable issue such as missing tables, corrupt binlogs, or unsupported statements. Review SHOW SLAVE STATUS, fix the underlying cause, and restart replication to resolve the problem.</p>
Fatal error: %s
Error 1593 appears in the replica’s error log and SHOW SLAVE STATUS when the SQL thread meets a condition it cannot recover from. MySQL stops applying relay log events to protect data consistency.
The error string reads "Fatal error: %s" where %s is replaced by the specific internal failure, such as a duplicate key violation or missing table definition. Immediate attention is required because replication is halted until the issue is fixed.
The SQL thread can fail if it replays a DDL or DML event that conflicts with data on the replica. Examples include duplicate primary keys, absent tables, or incompatible schema changes.
Corrupt or truncated binary logs, disk space exhaustion, file-system permission changes, and bugs in storage engines also trigger the fatal condition.
First, run SHOW SLAVE STATUSG to capture Last_SQL_Error and Relay_Log_File/Relay_Log_Pos. The message pinpoints the failing statement.
Correct the underlying issue: rebuild the missing table, delete conflicting rows, or re-extract clean logs from the primary. Then restart the SQL thread with START SLAVE SQL_THREAD or START REPLICA SQL_THREAD in MySQL 8.
If a duplicate key causes the stop, safely delete or update the offending row and use SET GLOBAL SQL_SLAVE_SKIP_COUNTER = 1 to skip the event, then restart the thread.
For schema mismatches, apply the same DDL change on the replica or perform a fresh clone using mysqldump, Xtrabackup, or MySQL Clone plugin.
Always apply schema changes in a controlled rollout using pt-online-schema-change or gh-ost to keep primary and replicas consistent.
Enable GTID replication and use crash-safe tablespaces so replicas can auto-recover after transient faults. Monitor the error log and replication lag with tools like Prometheus or MySQL Enterprise Monitor.
Error 1032 (ER_KEY_NOT_FOUND) often appears as the root cause inside Error 1593. Error 1062 (ER_DUP_ENTRY) is another frequent trigger. Fixing those underlying issues clears Error 1593.
Error 1201 (ER_MASTER_FATAL_ERROR_READING_BINLOG) affects the IO thread rather than the SQL thread. Solutions focus on network connectivity and binary log integrity.
The relay log contains DML for a table or column that does not yet exist on the replica.
An INSERT from the relay log violates a uniqueness constraint and stops the SQL thread.
Replication cannot parse a malformed event produced by crash or disk issues on the primary.
A feature present in the primary’s version is unknown to the replica, causing fatal failure.
The replica cannot write to data files or relay logs, triggering an unrecoverable stop.
Occurs when the SQL thread cannot find a referenced row; often escalates into Error 1593.
Triggered by duplicate keys during replication. Skipping or fixing the row resolves both errors.
Indicates a fatal error in the IO thread, typically due to inaccessible binary logs on the primary.
Signals problems reading the relay log, sometimes preceding Error 1593.
Skipping a single event can restore replication quickly, but only do so after confirming it will not create data inconsistencies. Always take a backup first.
The error itself does not cause loss, but it stops replication. If the underlying issue corrupted data, you must restore consistency manually.
Set up alerts on Seconds_Behind_Master, Replica_running status, and error log patterns. Tools like Prometheus mysqld_exporter or MySQL Enterprise Monitor help.
Galaxy’s versioned, endorsed SQL library reduces accidental schema changes that break replication. Its AI copilot can review DDL for safety before deployment.
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