The bug tracker can be found at http://bugs.contribs.org.
The bugtracker is for reporting issues with SME Server and is used extensively by the developers to track problems and new feature request needed for development of SME Server. Here you should report all problems you experience with SME Server installation. All problems or issues you experience with stock SME Server, SME Server contribs or with other products like the wiki and forums should be reported in the bugtracker and not in the forums.
For more information on how to work with the bugtracker please read Bugzilla Help.