Problem

Users cannot log in. 

This error is displayed in the UI:

The following appears in the atlassian-confluence.log:

2015-03-04 16:54:38,535 WARN [http-bio-8564-exec-9] [atlassian.seraph.auth.DefaultAuthenticator] login login : 'admin' tried to login but they do not have USE permission or weren't found. Deleting remember me cookie.

The following (or similar) may appear above the aforementioned error:

2015-03-05 22:32:22,843 INFO [read-only-transaction:thread-1] [atlassian.confluence.user.DefaultUserAccessor] getUserNamesWithConfluenceAccess Could not find group configured with USE permission: confluence-administrators
2015-03-05 22:32:22,843 INFO [read-only-transaction:thread-1] [atlassian.confluence.user.DefaultUserAccessor] getUserNamesWithConfluenceAccess Could not find group configured with USE permission: confluence-users

The user(s) and group(s) mentioned in the logs actually do exist in the database.

Diagnosis

Environment

• SQL Server database
• Data types on certain columns were changed to the recommended Unicode data types (e.g., char --> nchar)  

Diagnostic Steps

• Check the length of the active columns in the cwd_user and cwd_directory tables:

  EXEC sp_help 'cwd_directory';
  EXEC sp_help 'cwd_user';
  

Cause

By default, the length of the active column in the cwd_user and cwd_directory tables is one (1) character. If that column is increased to two characters, which can happen when changing the data type to one that supports Unicode (like nchar), that creates a situation where Confluence cannot find users or groups that have USE permission. As a result, users will not be able to log in, even though they exist in the database and have the necessary permissions.

Resolution 

• Modify the affected tables (cwd_user or cwd_directory or both) by changing the length of the active column back to one character:

  ALTER TABLE table_name
  ALTER COLUMN active nchar(1);

  Always backup your data before performing any modifications to the database.

• Restart Confluence or flush the Confluence caches