After upgrading to DocuWare 6.10/6.11, Single Sign-On (Windows Authentication) does not work anymore. 

Since version 6.10, the database field, where the domain name is registered, is case-sensitive.
This means that if the domain name is e.g. "PetersEngineering" but in DocuWare the name was specified lower case ("petersengineering"), the domain name is no longer recognized.

Amend the domain name via the DocuWare Administration:

As an alternative you may amend the content of column "windomain" of table "DWUser" in database "DWSystem"
Example: UPDATE DWUser SET windomain='PetersEngineering' WHERE windomain='petersengineering';

Note: Please always backup your databases before performing any changes directly in the database!