Earlier today I upgraded my cPanel server using EasyApache from PHP 5.3 to 5.4, I also included Xcache, and I think mod_pagespeed was also added.
After the upgrade all my SilverStripe 3.1 sites were just returning 500 Server Errors, which I eventually tracked down in the logs as:
Premature end of script headers: main.php
Doing a dev/build on each site seemed to fix the issue, but it was a real pain to have to enable dev mode on each site config, and then dev/build (I have over 50 SilverStripe sites on my server).
Any idea what caused this? My guess is some kind of database issue. Something to do with InnoDB? Which I don't know much about.
I wasn't able to work out exactly why a dev/build fixed the sites, but I'd like to understand in order to avoid the issue in future.
I've still got a few (unused) sites that I haven't run dev/build on yet, so happy to have a play if you have any suggestions to work out exactly what caused this.