If you're using WindowsMembershipProvider (or MultiplexingMembershipProvider), check if you're connected to the domain.
If you're using SqlServerMembershipProvider, check if the user account is locked.
If you don't get any error messages on the login screen, that means your username and password are correct, but you don't have necessary permissions to access edit / admin mode.
Check that you are connected to AD. If you are not, disable windows membership provider in web.config. Sometimes you get a trust issue vs AD that prevents login in dev environments.
@dejan and @daniel
Earlier the question was not completed .Now i have updated the question.
Ok. Check he isn't locked out and has correct roles. Also try resetting password in admin...
Since you can log in with other account is not the classic ad trust issue so scratch that...
How to check whether user is locked out or not?
how to reset password from admin.I am unable to search the user..
while searching the error I am getting is:
Item has already been added. Key in dictionary: 'email@example.com' Key being added: 'firstname.lastname@example.org'
It looks like your DB is corrupted. Open aspnet_Users table and check if you have duplicate entries in LoweredUserName column.
Oh...unable to search for user as well...sounds like a duplicate user name then like Dejan is suggesting. Are you only using Sql membership provider? Maybe you have same username on 2 providers?
Thanks Daniel and dejan..Multiple user info was the reason for this..Thanks a lot...
Tough bug. Sweet you could resolve it!
Unable to log in with a user though user exist in CMS.I have a existing user in CMS but he is not able to log in to the system.When I search the user in admin mode with working credential then error I am getting is Item has already been added. Key in dictionary: 'email@example.com' Key being added: 'firstname.lastname@example.org'
email@example.com is the email with which he is registered.
I am able to search users for which credential is working.
Does anyone encounter this kind of problem.Your help will be highly appreciated...
Thanks in advance..