ERROR 3021 (HY000): This operation cannot be performed with a running slave io thread; run STOP SLAVE IO_THREAD FOR CHANNEL '' first.

error¶

mysql master-slave service, stop the slave server from the machine to execute the start copy command error

mysql> change master to master_host='192.168.0.99',master_port=3307,master_user='copy',master_password='copy',master_log_file='mysql-bin.000001',master_log_pos=154;
ERROR 3021 (HY000): This operation cannot be performed with a running slave io thread; run STOP SLAVE IO_THREAD FOR CHANNEL '' first.

Troubleshoot¶

The slave server cannot be modified while the io thread is started, so we need to close the io thread

mysql> STOP SLAVE IO_THREAD;
Query OK, 0 rows affected (0.00 sec)
mysql> change master to master_host='192.168.0.99',master_port=3307,master_user='copy',master_password='copy',master_log_file='mysql-bin.000001',master_log_pos=154;
Query OK, 0 rows affected, 2 warnings (0.00 sec)
mysql> START SLAVE IO_THREAD;
Query OK, 0 rows affected (0.00 sec)