diff --git a/src/Web/Users/Types.hs b/src/Web/Users/Types.hs
--- a/src/Web/Users/Types.hs
+++ b/src/Web/Users/Types.hs
@@ -17,7 +17,6 @@
     )
 where
 
-import Control.Applicative
 import Crypto.BCrypt
 import Data.Aeson
 import Data.Int
@@ -30,16 +29,27 @@
 import qualified Data.Text.Encoding as T
 import qualified System.IO.Unsafe as U
 
+{-# DEPRECATED UsernameOrEmailAlreadyTaken "Please use the more specific error constructors." #-}
+
 -- | Errors that happen on storage level during user creation
 data CreateUserError
    = UsernameOrEmailAlreadyTaken
    | InvalidPassword
+   | UsernameAlreadyTaken
+   | EmailAlreadyTaken
+   | UsernameAndEmailAlreadyTaken
    deriving (Show, Eq)
 
+{-# DEPRECATED UsernameOrEmailAlreadyExists "Please use the more descriptive constructors instead." #-}
+{-# DEPRECATED UserDoesntExit "Please use UserDoesntExist instead." #-}
+
 -- | Errors that happen on storage level during user updating
 data UpdateUserError
    = UsernameOrEmailAlreadyExists
+   | UsernameAlreadyExists
+   | EmailAlreadyExists
    | UserDoesntExit
+   | UserDoesntExist
    deriving (Show, Eq)
 
 -- | Errors that happen on storage level during token actions
@@ -88,6 +98,9 @@
     withAuthUser :: FromJSON a => b -> T.Text -> (User a -> Bool) -> (UserId b -> IO r) -> IO (Maybe r)
     -- | Verify a 'SessionId'. The session duration can be extended by 'NominalDiffTime'
     verifySession :: b -> SessionId -> NominalDiffTime -> IO (Maybe (UserId b))
+    -- | Force create a session for a user. This is useful for support/admin login.
+    -- If the user does not exist, this will fail.
+    createSession :: b -> UserId b -> NominalDiffTime -> IO (Maybe SessionId)
     -- | Destroy a session
     destroySession :: b -> SessionId -> IO ()
     -- | Request a 'PasswordResetToken' for a given user, valid for 'NominalDiffTime'
diff --git a/users.cabal b/users.cabal
--- a/users.cabal
+++ b/users.cabal
@@ -1,5 +1,5 @@
 name:                users
-version:             0.3.0.0
+version:             0.4.0.0
 synopsis:            A library simplifying user management for web applications
 description:         Scrap the boilerplate for managing user accounts in web applications
                      .
@@ -18,6 +18,7 @@
                      Current Backends:
                      .
                      * <http://hackage.haskell.org/package/users-postgresql-simple PostgreSQL-Simple Backend>
+                     * <http://hackage.haskell.org/package/users-persistent Persistent Backend>
                      .
 homepage:            https://github.com/agrafix/users
 bug-reports:         https://github.com/agrafix/users/issues