phpBB2
phpBB2 was the predecessor of the present-day phpBB3. Developed during 2001-2002, the source code was written primarily to run on PHP 3.0 and 4.0 (version 2.0.13 upped the minimum requirement to PHP 4.0.3 due to a necessary security fix), and by the time that phpBB3 was released in late 2007, the developers and other team members felt that it no longer met their quality coding standards, and announced plans for the retirement/end of support of 2.0.x within a few months of 3.0.0’s release. phpBB2 was never officially supported under PHP 5. Although many users had no problems running it after making a few changes to PHP 5’s default configuration settings, the teams chose not to offer support for this configuration.