Mod Note: The Thread Title Need PHP version : 5.4.15, instead of 5. Sorry I'm performing a test upgrade of my latest Xenforo on a clone server. I successfully upgraded php from 5.2 -> 5.4.15 and the other test server details are as follows. Apache version: 2.2.24 PHP version:5.4.15 MySQL version: 5.0.96-community After upgrading the site, I'm getting "An unexpected error occurred. Please try again later." on the site. I've few questions: 1. What's the right way to fix that error? 2. What's the latest MySQL version I can upgrade to without worrying about errors. 3. If there are issues running 5.4.15; which is the latest PHP I can upgrade to without worrying about errors?