This error can be found in the mingle logs and is an error that can mean a number of things. One of the most common mistakes when this error is seen is when you have a typo in your login name. It could also mean that the settings in your auth_config.yml file are not setup correctly. In which case, we recommend that you run the LDAP test tool that is attached and contact support at email@example.com.
[2013-08-20 10:27:31,608] [btpool0-4] [com.thoughtworks.mingle] ERROR Mingle is able to connect to the LDAP server specified in /mingle/data/config/auth_config.yml but find multiple users with the same login ID - johnr. If you suspect a serious problem, please run Mingle with log level set to DEBUG to see the full detail of this error.
[2013-08-20 10:27:31,611] [btpool0-4] [com.thoughtworks.mingle] ERROR User authentication failed : johnr