<p>Error 1804 arises when MySQL cannot delete Multi Threaded Slave worker metadata tables during RESET SLAVE, blocking replication cleanup.</p>
<p>MySQL Error 1804: ER_MTS_RESET_WORKERS means the server failed to remove worker info tables after RESET SLAVE, halting replication. Stop the replica, manually drop the leftover mysql.slave_worker_info tables, run RESET SLAVE ALL, then START SLAVE to resolve the issue.</p>
Cannot clean up worker info tables. Additional error
MySQL raises Error 1804 with the message "Cannot clean up worker info tables" when it attempts to delete replication worker metadata during RESET SLAVE or channel reconfiguration. The failure involves tables in the mysql schema that store Multi Threaded Slave (MTS) status.
The error aborts RESET SLAVE and leaves replication inactive. Until the obstructing tables are removed, subsequent replication commands will fail or hang.
The condition appears on replicas configured with slave_parallel_workers after running RESET SLAVE, CHANGE MASTER TO, or during server start if old worker tables persist.
Unexpected crashes or forced shutdowns can also leave these tables open, causing the cleanup routine to fail at the next restart.
Replication stoppage leads to data lag and inconsistent reads. Rapid removal of the tables restores replication, maintains data parity, and protects downstream analytics.
Locked files, corrupted tables, incorrect file permissions, or another session referencing mysql.slave_worker_info prevent MySQL from executing DROP TABLE during cleanup.
Stop replication, verify and drop the leftover worker tables, run RESET SLAVE ALL, and start replication again. A server restart may be required if file locks persist.
Corrupted tables respond to mysqlcheck or a direct DROP TABLE followed by InnoDB file-per-table reclaim. Permission problems require adjusting ownership or file system mount options.
Always stop replication cleanly before RESET SLAVE, enable crash-safe settings like sync_binlog and innodb_flush_log_at_trx_commit, and monitor the error log for worker cleanup warnings through Galaxy dashboards.
Similar replication issues include Error 1201 (ER_MASTER_INF), Error 1872 (ER_SLAVE_CHANNEL_SINGLE), and Error 1268 (ER_TOO_BIG_ROWSIZE). Each involves metadata cleanup or privilege corrections.
A lingering thread still references the mts_worker_info tables, preventing DROP TABLE during RESET SLAVE.
The mysqld user lacks permission to delete the .frm or .ibd files in the data directory, blocking cleanup.
Crash recovery or disk errors corrupt the worker info tables, causing internal engine failures when MySQL tries to drop them.
Occurs when the replica cannot update master info; often fixed by repairing mysql.slave_master_info.
Raised when a command requires a single channel but multiple channels exist; specify FOR CHANNEL to resolve.
Signals a row exceeds InnoDB page limits; solved by reducing columns or changing row format.
Stop replication, drop the residual mysql.slave_worker_info tables, run RESET SLAVE ALL, and then START SLAVE.
Yes, in most cases dropping the tables and running RESET SLAVE ALL is enough. Restart only if file locks persist.
No. These tables store replication state, not user data. Once replication restarts, state is rebuilt automatically.
Galaxy lets teams version and endorse replication maintenance scripts, ensuring the correct cleanup commands are always reused.
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