Please note that if Sitefinity is not letting you log in to the backend with this message, it might mean that either you do not have sufficient privileges (only users who belong to the BackendUsers role can access Sitefinity backend) or you might have replaced the site's configuration files with incorrect ones. In order for Sitefinity to correctly resolve a role it needs to have the Role IDs in App_Data/Sitefintiy/Configuration/SecurityConfig.config and the ones in the sf_roles database table to match exactly.
the Telerik team
Do you want to have your say in the Sitefinity development roadmap? Do you want to know when a feature you requested is added or when a bug fixed? Explore the Telerik Public Issue Tracking
system and vote to affect the priority of the items