ACS user unknown though username in Server

Question

            All, Im facing very strange issue with my TACACS authentication. Normaly i connect my DC via SSL Anyconnect VPN then access all the Network devices, but since last week when i try to connect ASA i couldnt log in. I have user name in ACS server and the password authentication would redirect to RSA server. I can access other devices using my TACACS username and RSA passcode, but not only the ASA box. As rest of my team member can still access the ASA with their userid and passcode i dont think any issue in ASA box.
The error log message in ACS server is ACS user unknown.       

Answer 1

To me it seems the shared secret being used on ASA to communicate with tacacs is mis-matched and that's a reason you  are getting "ACS user unknown". This should be a problem all users who are trying to do ssh on ASA and authenticating against tacacs server. Why share-secret could be an issue because the shared secret being used to encrypt the packet is not same while decryption and that's why we are seeing unknown username.
~BR
Jatin Katyal
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