Today, started to test moving some of our PHP4 apps to PHP5.1.1. Some of this code was written for PHP 4.0.6, over 3 years ago. The migration so far has been relatively painless. Here are some of the problems we encountered.
Included in his list are things like:
- issues with code generators (created in PHP4) and pass by reference problems
- the classic register_globals issues
- the lack of an open source opcode cache for Windows
- and more...