I have been trying to turn on SSL on one of my websites now I have a (cheap at £14) RapidSSL certificate. The site (hosted on CentOS, CPanel, WHM) was working fine under HTTP, but when I tried to access using HTTPS I got a 500 Internal Server error.

Looking at the Apache logs through my CPanel, I found the following:

“SoftException in Application.cpp:NNN: Mismatch between target UID (NN) and UID (NNN)” (Ns are numbers, changed to protect the innocent).

I traced this down via a number of different pages which all pointed to the fact that I should be using FastCGI rather than suPHP as my Apache PHP handler.

NB I chose FastCGI over other options thanks to a warning about WordPress: everything has been just working for me, and I didn’t want to break it.

I recompiled Apache with the FastCGI module through WHM’s EasyApache and everything appears to work. I’ll hold off making further configuration changes for a while.