I am trying to connect for on-premise TFS, and alwais get the same error:
"Unexpected character encountered while parsing value: <. Path '', line 0, position 0."
and my Project Collection Url, user and password (domain\user) are correct.
Unfortunately, TFS 2012 is not supported, as it has completely different API compared to TFS 2013 and higher.
When your TFS gets upgraded, you can give CatLight another try.
What version of TFS do you use?
This can happen if some error happened in TFS and it returned html page instead of JSON reponse.
To see what happened, you can use Fiddler web debugging proxy that will show requests that CatLight makes and TFS responses.
