Connection changed from write to read-only mode in single connection

We have two MySQL nodes and we are connecting with them using MMM write VIP. We are executing certain insert sqls in one connection. But recently we have found that after some insert it changed connection from write to read-only mode and then all the remaining insert sqls are fail. It is happening approximately one time in week and for very few certain time. We are getting below error.

Fatal error: Uncaught exception 'PDOException' with message 'SQLSTATE[HY000]: General error: 1290 The MySQL server is running with the --read-only option so it cannot execute this statement'

Also we have found that switching write VIP from one MySQL node to another MySQL node it is not synchronized properly and due to that same auto incremented primary key generated two times and at the end of replication one of the record missed.