Traq 4.0 is a complete rewrite from Traq 3.x, the major changes are:
PHP 5.5 is required
Traq 4.0 might run on 5.4, but it is not supported.
- New framework: Avalon 2.0
Avalon 2.0 uses the Doctrine DBAL which supports more database systems such as PostgreSQL.
BCrypt passwords required
Anyone logging into a Traq 4.0 installation that was upgraded from Traq 3.x will be required to change their password if they are still using a