Comment 2 for bug 2003744

So the error message is coming from hvac, and this post gives an interesting perspective on it: https://support.hashicorp.com/hc/en-us/articles/4404634420755-Why-am-I-seeing-context-deadline-exceeded-errors

An interesting section:

The error 'context deadline exceeded' means that we ran into a situation where a given action was not completed in an expected timeframe. For Vault this is typically going to be related to a network connection made to an external system such as a database or even a storage backend such as Consul.

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I'm going to hazard a guess, and suggest that we look at the health/status of the mysql database at the time the error occured; e.g. the /var/log/mysql/error.log files will help to indicate what the status of the cluster was during the above error trace.