Unexpected "Error restarting mysql" events

This is most likely your Aurora Replica needing to restart for its maintenance. Check for metric AuroraReplicaLag if there have been some lags detected.

https://aws.amazon.com/premiumsupport/knowledge-center/aurora-read-replica-restart/

Thank you for your answer. I've checked the replication lag, however it is only about 19ms on my reader instances, so I don't think this is the reason. Additionally I've now started seeing these events ("Error restarting mysql: java.io.IOException: No such process") to start happening on the writer instances as well every couple of hours.

We are seeing the same problem on a single read/writer Aurora instance with no replicas. First occurence of this issue was on 2022-01-17 running 2.10.1.

We have upgraded meanwhile to 2.10.2 and this "Error restarting mysql: java.io.IOException: No such process" event still keeps re-appearing after upgrade / instance restart.

I talked with the AWS support and apparently this is an internal event which should not be "customer visible" and can be ignored:

Although these events may indicate an error, they are meant for internal monitoring, and can be safely ignored. Hence, we are working on a fix for removing this messaging from Aurora logging. Until then, these messages will emitted from the logs and should be ignored. The Aurora MySQL service is otherwise fully operational after a reboot with this log messaging.