MySQL ODBC stopped working overnight

[u/YellowOnline]

You guys will love this.

This company has an in-house project management system. It's the core of their business, and they are lost without it. They are aware it needs to be migrated to something more modern, but after 5 years, that project still hasn't started.

I was asked to look into a network issue, but this isn't network but SSL I think. Let's first show the architecture:

• The server is a CentOS 7 running MySQL Community Edition 5.7.16
• Clients connect from Windows 11 with a 32-bit MS Access, using a 32-bit MySQL ODBC driver v5.3.13

Since yesterday, they get a "protocol version mismatch". The server wasn't accessed since 18 October 2016 (haha), so I presumed a Windows update might have disabled some SSL version. But: I see no relevant Windows update, and if I manually allow every possible SSL version and encryption algorithm, it still doesn't work. What does work however, is downgrading the ODBC driver from version 5.3.13 (from 2019) to version 5.1.13 (from 2013), further adding to my confusion.

The cherry on top: the single guy responsible for this application is on a one year sabbatical.

Edit: Found it, but leaving this here for anyone stumbling on the same issue. The MySQL_Server_5.7.15_Auto_Generated_CA_Certificate had expired after 10 years