Cannot upgrade to Confluence 3.1 when using Crowd integration

Despite that the admin username and password is valid, upgrading a Confluence instance that is connected to Crowd to Confluence version 3.1 returns this error:

You did not enter a valid username and password for a Confluence administrator.

Confluence 3.1 requires a version 2 license key, for this it requires admin user's username and password to complete the procedure. Unfortunately it does not honor Crowd Confluence Admin user.