Are all OPS agents in your cluster in good communication with each other? Do your network and security settings permit communication between OPS agents? This message
Timed out while sending API message means that the primary OPS agent tried to send instructions to a follower OPS agent to upgrade itself, but it was unable to communicate and timed out.
Check current OPS state by running the command below on the primary OPS agent, and also SSH into each of the other hosts and run it there.
If one of the agents shows itself as offline or fails to respond when you run that command on its host, then start it locally on that host with the command:
Once all OPS agents are online try the upgrade again.
The agent list should be the same on all agents. However in version 5.8 if there was disconnectivity between OPS agents it could be hard to diagnose without checking each agent individually, because the primary OPS agent would assume everything was fine until it heard otherwise, which wouldn’t happen if a follower was unable to communicate. Connectivity between OPS agents was dramatically improved in the fixes in OPS version 6.5.9. Once your MemSQL cluster is any version of 6.X.X be sure to upgrade OPS to the most recent version, which is currently 6.7.5. For more information see the OPS release notes: https://docs.memsql.com/memsql-ops/v6.7/memsql-ops-releases/
Note that if your MemSQL version is less than 5.8 you will have to upgrade to 5.8 before you can upgrade it to any 6.X version. For more information on upgrading from version 5.8 to any 6.X version see our docs: https://docs.memsql.com/operational-manual/v5.8/upgrading-memsql/
As a side note, the message
You have mail in /var/spool/mail/root does not have to do with MemSQL nor with OPS. It is a system message, resulting from some system level task like cron job, or system security report that had an output but nowhere to put it. For more information on reading this message, see this external article: https://askubuntu.com/questions/1058894/you-have-mail-in-var-spool-mail-root