MySQL Last_Errno: 1396

MySQL 主备数据库切换报错1396处理方法，操作步骤如下：

mysql> show slave status \G;
*************************** 1. row ***************************
               Slave_IO_State: Waiting for master to send event
                  Master_Host: 196.55.3.180
                  Master_User: repl
                  Master_Port: 3311
                Connect_Retry: 60
              Master_Log_File: mysql-bin.000002
          Read_Master_Log_Pos: 1674
               Relay_Log_File: relay-log.000002
                Relay_Log_Pos: 367
        Relay_Master_Log_File: mysql-bin.000001
             Slave_IO_Running: Yes
            Slave_SQL_Running: No
              Replicate_Do_DB: 
          Replicate_Ignore_DB: 
           Replicate_Do_Table: 
       Replicate_Ignore_Table: 
      Replicate_Wild_Do_Table: 
  Replicate_Wild_Ignore_Table: 
                   Last_Errno: 1396
                   Last_Error: Error 'Operation CREATE USER failed for 'repl'@'%'' on query. Default database: ''. Query: 'CREATE USER 'repl'@'%' IDENTIFIED WITH 'mysql_native_password' AS '*2813999EE1B5ABB4D8C2D12234F0649DF6A9BC19''
                 Skip_Counter: 0
          Exec_Master_Log_Pos: 154
              Relay_Log_Space: 2217
              Until_Condition: None
               Until_Log_File: 
                Until_Log_Pos: 0
           Master_SSL_Allowed: No
           Master_SSL_CA_File: 
           Master_SSL_CA_Path: 
              Master_SSL_Cert: 
            Master_SSL_Cipher: 
               Master_SSL_Key: 
        Seconds_Behind_Master: NULL
Master_SSL_Verify_Server_Cert: No
                Last_IO_Errno: 0
                Last_IO_Error: 
               Last_SQL_Errno: 1396
               Last_SQL_Error: Error 'Operation CREATE USER failed for 'repl'@'%'' on query. Default database: ''. Query: 'CREATE USER 'repl'@'%' IDENTIFIED WITH 'mysql_native_password' AS '*2813999EE1B5ABB4D8C2D12234F0649DF6A9BC19''
  Replicate_Ignore_Server_Ids: 
             Master_Server_Id: 10003
                  Master_UUID: 84aa2159-14f8-11ea-bc00-00505687741b
             Master_Info_File: mysql.slave_master_info
                    SQL_Delay: 0
          SQL_Remaining_Delay: NULL
      Slave_SQL_Running_State: 
           Master_Retry_Count: 86400
                  Master_Bind: 
      Last_IO_Error_Timestamp: 
     Last_SQL_Error_Timestamp: 191204 19:51:57
               Master_SSL_Crl: 
           Master_SSL_Crlpath: 
           Retrieved_Gtid_Set: 1b4e1296-14f7-11ea-8332-005056873bbd:1-2,
84aa2159-14f8-11ea-bc00-00505687741b:1
            Executed_Gtid_Set: 183c6bb2-5f65-11e9-b3cf-0050568745fc:1-8807
                Auto_Position: 1
         Replicate_Rewrite_DB: 
                 Channel_Name: 
           Master_TLS_Version: 
1 row in set (0.00 sec)

ERROR: 
No query specified

mysql> show master status;
+------------------+----------+--------------+------------------+---------------------------------------------+
| File             | Position | Binlog_Do_DB | Binlog_Ignore_DB | Executed_Gtid_Set                           |
+------------------+----------+--------------+------------------+---------------------------------------------+
| mysql-bin.000006 |  5719971 |              |                  | 183c6bb2-5f65-11e9-b3cf-0050568745fc:1-8807 |
+------------------+----------+--------------+------------------+---------------------------------------------+
1 row in set (0.00 sec)

mysql> select * from performance_schema.replication_applier_status_by_worker where LAST_ERROR_NUMBER=1396;
+--------------+-----------+-----------+---------------+----------------------------------------+-------------------+------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+----------------------+
| CHANNEL_NAME | WORKER_ID | THREAD_ID | SERVICE_STATE | LAST_SEEN_TRANSACTION                  | LAST_ERROR_NUMBER | LAST_ERROR_MESSAGE                                                                                                                                                                                         | LAST_ERROR_TIMESTAMP |
+--------------+-----------+-----------+---------------+----------------------------------------+-------------------+------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+----------------------+
|              |         0 |      NULL | OFF           | 1b4e1296-14f7-11ea-8332-005056873bbd:1 |              1396 | Error 'Operation CREATE USER failed for 'repl'@'%'' on query. Default database: ''. Query: 'CREATE USER 'repl'@'%' IDENTIFIED WITH 'mysql_native_password' AS '*2813999EE1B5ABB4D8C2D12234F0649DF6A9BC19'' | 2019-12-04 20:02:13  |
+--------------+-----------+-----------+---------------+----------------------------------------+-------------------+------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+----------------------+
1 row in set (0.00 sec)

mysql> stop slave;
Query OK, 0 rows affected (0.00 sec)

mysql> set @@session.gtid_next='1b4e1296-14f7-11ea-8332-005056873bbd:1';
Query OK, 0 rows affected (0.00 sec)

mysql> begin;
Query OK, 0 rows affected (0.00 sec)

mysql> commit;
Query OK, 0 rows affected (0.00 sec)

mysql> set @@session.gtid_next=automatic;
Query OK, 0 rows affected (0.00 sec)

mysql> start slave;
Query OK, 0 rows affected, 1 warning (0.00 sec)

mysql> show slave status\G;
*************************** 1. row ***************************
               Slave_IO_State: Waiting for master to send event
                  Master_Host: 196.55.3.180
                  Master_User: repl
                  Master_Port: 3311
                Connect_Retry: 60
              Master_Log_File: mysql-bin.000002
          Read_Master_Log_Pos: 1674
               Relay_Log_File: relay-log.000005
                Relay_Log_Pos: 494
        Relay_Master_Log_File: mysql-bin.000002
             Slave_IO_Running: Yes
            Slave_SQL_Running: Yes
              Replicate_Do_DB: 
          Replicate_Ignore_DB: 
           Replicate_Do_Table: 
       Replicate_Ignore_Table: 
      Replicate_Wild_Do_Table: 
  Replicate_Wild_Ignore_Table: 
                   Last_Errno: 0
                   Last_Error: 
                 Skip_Counter: 0
          Exec_Master_Log_Pos: 1674
              Relay_Log_Space: 1154
              Until_Condition: None
               Until_Log_File: 
                Until_Log_Pos: 0
           Master_SSL_Allowed: No
           Master_SSL_CA_File: 
           Master_SSL_CA_Path: 
              Master_SSL_Cert: 
            Master_SSL_Cipher: 
               Master_SSL_Key: 
        Seconds_Behind_Master: 0
Master_SSL_Verify_Server_Cert: No
                Last_IO_Errno: 0
                Last_IO_Error: 
               Last_SQL_Errno: 0
               Last_SQL_Error: 
  Replicate_Ignore_Server_Ids: 
             Master_Server_Id: 10003
                  Master_UUID: 84aa2159-14f8-11ea-bc00-00505687741b
             Master_Info_File: mysql.slave_master_info
                    SQL_Delay: 0
          SQL_Remaining_Delay: NULL
      Slave_SQL_Running_State: Slave has read all relay log; waiting for more updates
           Master_Retry_Count: 86400
                  Master_Bind: 
      Last_IO_Error_Timestamp: 
     Last_SQL_Error_Timestamp: 
               Master_SSL_Crl: 
           Master_SSL_Crlpath: 
           Retrieved_Gtid_Set: 1b4e1296-14f7-11ea-8332-005056873bbd:1-2,
84aa2159-14f8-11ea-bc00-00505687741b:1
            Executed_Gtid_Set: 183c6bb2-5f65-11e9-b3cf-0050568745fc:1-8807,
1b4e1296-14f7-11ea-8332-005056873bbd:1-2,
84aa2159-14f8-11ea-bc00-00505687741b:1
                Auto_Position: 1
         Replicate_Rewrite_DB: 
                 Channel_Name: 
           Master_TLS_Version: 
1 row in set (0.00 sec)

ERROR: 
No query specified

mysql>