"user does not exist or is not unique"
- This error could come from a mapping with the user source that is not available (Active Directory, Single Sign On solution)
- Try to reconnect the source
Context and detailed resolution :
SharePoint + Ping federate (claim provider) for the authentication. The web application was configured to use ping federate. Then we did some configuration about sharepoint and ping federate by powershell (we added a new realm in ping and sharepoint), and the people people would show users from ping but issued, when we clicked on ok, by "user does not exist or is not unique".
=> As it was for a test environment, recreating the web application, seemed to refresh the custom claim provider and solved the problem.
In the next post i'll give an global overview of a Claim provider, Single Sign on situation. From a sharepoint A, logged by Active directoy, we will be able to connect to a sharepoint B, by transfering the authentication. Transparent for the user and save him the time to relog on the SharePoint B environment.