What did you do to cause this? Did a fresh install of Traq
What page were you on? /admin/plugins
What PHP and MySQL versions do you run? PHP 5.4.12-1~dotdeb.1 and MySQL 5.5.30-1~dotdeb.0-log on a debian 64bit box
Describe the defect: I think the PHP error describes it best: "PHP Parse error: syntax error, unexpected '<' in /vendor/traq/plugins/nl2br/nl2br.php on line 2"
There are two <?php instead of one ;)