there is quite a lot of writing across the web on this ASP.net issue:
Membership credential verification failed.
Name to authenticate: userXYZ
When you have role, memberhip, or other providers configured in your ASP.net application, you have to remember to set the ApplicationName property in each of the provider entries in your web.config file. That’s clear. But what if the message still comes up?
In my case I was using forms authentication against Active Directory with a custom role provider. The odd thing was that only a few of the users could not perform a correct login. Others were signing in just ok. So, after checking the AD properties of the user objects (there was a suggestion that it may be caused by similar objects in different OU’s), then analyzing the role logic of the custom provider, nothing seemed to be causing the trouble.
The actual reason was very simple. The users which had problems signing in had cookies disabled in their browsers, hence the forms authentication could not store the session data on client side. So, one should have in mind, that the windows server log entries with the „Membership credential verification failed” information message could also be caused by such a trivial thing as unavailable cookies in user’s browsers.
Hope this helps,