Failure after server upgrade

[mbs]

Have a couple of sites running - sorry, not sure which version. There was a cPanel upgrade to v64 build 17 which has stopped cms from working. Just get error 500 from browser when trying to access.

Sorry to be a bit vague but wondering if there's an easy way to recover old sites.

[Jos]

Maybe this helps: https://docs.cmsmadesimple.org/upgrading/old-versions