Hello everyone!

I'm having this issue, I'm trying to login to my website with a registred user.

But when I'm about t oget redirected to my "authenticated" page I get this error: 

System.InvalidOperationException: Cannot decrypt password

Stack trace:

InvalidOperationException: Cannot decrypt password]
   EPiServer.Common.Security.HMACPasswordProvider.DecryptPassword(Byte[] ciphertext) +60
   EPiServer.Common.Web.Authorization.Integrator.SynchronizeUser(MembershipUser membershipUser, String password, Boolean enableCreateNew) +1116
   System.Web.SyncEventExecutionStep.System.Web.HttpApplication.IExecutionStep.Execute() +80
   System.Web.HttpApplication.ExecuteStep(IExecutionStep step, Boolean& completedSynchronously) +165

Anyone have any idea on what this could be about? 
If I check my database I can see that the password in decrypted so I don't see why It's complaining.