The new release of PHP 5.3 brought many important additions and changes to PHP. Although longly awaited, some of the changes are not backwards compatible. Thus, code that worked fine with 5.2 may produce warnings or fail in 5.3.
Quick research shows that most prominent applications had to be patched or changed, even though minimally, to work cleanly with 5.3. To help people to convert their web applications to 5.3, I present here a migration script that would allow you to inspect your applications for potential migration problems.