Cannot sign in to Lync Share on Facebook Post on reddit Tweet on Twitter Share on LinkedIn Home › Forums › Messaging Software › Skype for Business Server › Cannot sign in to Lync This topic has 2 replies, 3 voices, and was last updated 6 years, 9 months ago by realwheel. Viewing 1 post (of 1 total) Author Posts sreeve29Member Dec 12, 2014 at 8:23 am #164650 I am able to log into my domain with the username and domain. I do this when I connect via RDP. I have enabled this user in the Lync Control Panel. (this all worked fine before, but I re-built my DC/DNC/CA server and now it’s not working) The error message I’m getting is “Cannot sign in to Lync” Lync was unable to sign in. Please verify your logon credentials and try again. If the problem continues, please contact your support team. I’ve turned on Lync Server Logging, and I put it into the u2.txt attachment. Around line 100, there seem to be error messages. On line 763 is the 401 Unauthorized message. Any suggestions would be greatly appreciated. Author Posts Viewing 1 post (of 1 total) You must be logged in to reply to this topic.