<p>MySQL cannot initialize the replica's relay log position, so replication stops.</p>
<p>ER_RELAY_LOG_INIT shows up when a MySQL replica cannot create or read its relay log coordinates, so the SQL thread will not start. Verify the relay-log.info file, disk permissions, and relay log integrity, then rebuild the relay logs with RESET SLAVE or CHANGE MASTER to resume replication.</p>
Failed initializing relay log position: %s
Error 1380 means the replica SQL thread failed while setting its starting relay log file and position. MySQL therefore cannot apply any further events from the master, and replication stops with a critical status.
The message is written to the replica error log during START SLAVE or server startup when replication is enabled. It usually follows crashes, abrupt shutdowns, or manual deletion of relay logs.
Until the relay log position is initialized, data on the replica lags indefinitely. This gap can break read scaling, disaster-recovery plans, and analytics workloads that depend on near-real-time data.
Most cases trace back to missing relay-log info metadata, file permission issues, or corruption inside existing relay log files after disk or network faults.
Identify the broken relay log coordinates, recreate metadata, and restart replication. The safest path is to reset the relay logs, but advanced users can also point CHANGE MASTER to a known good file and position to avoid a full resync.
Scenario: relay_log_info is gone after a disk cleanup. Solution: restore the file or run RESET SLAVE to regenerate it.
Scenario: the replica ran out of disk space and truncated a relay log. Solution: free space, purge bad files, and pull fresh logs from the master.
Keep relay logs on dedicated, monitored storage, enable automatic relay_log_purge, and schedule regular checks with SHOW SLAVE STATUS. Galaxy’s versioned SQL allows quick validation of replication health queries and sharing them across teams.
Replication errors 1593, 1594, and 1872 often happen together when I/O or SQL threads fail for similar reasons. Review each error line and apply matching fixes.
The relay-log.info or relay_log_info repository table was deleted or corrupted, leaving MySQL without starting coordinates.
OS-level changes removed read or write rights on the relay-log directory, so the SQL thread cannot open the log files.
Unexpected shutdowns or storage failures introduced invalid checksums, causing the SQL thread to abort initialization.
Administrators sometimes purge relay logs to free space without issuing RESET SLAVE, breaking the position pointers.
Occurs when the I/O thread cannot read from a relay log file because of corruption or missing file.
Triggers when the replica cannot write to its relay log directory, often due to disk full or permission issues.
Signals a general failure processing a relay log event after initialization, usually following Error 1380.
No. ER_RELAY_LOG_INIT is exclusive to replicas because only they manage relay logs.
RESET SLAVE removes relay logs and replication metadata but leaves existing data intact. Always back up before running it.
Galaxy lets you save a SHOW SLAVE STATUS query in a shared collection and schedule it, so teams see replication breaks instantly.
Only the replica is affected. The primary stays online, and applications reading from the replica can failover to other nodes.
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