The error occured while attempting to login to the tool.
Followed the Cisco Recommendation below:
The following has to be checked:-
HTTP proxy server
TCP port 6293 is blocked
Both checked, As the entire network uses Proxy Settings so added the UCCX Server as an exeption in the proxy Settings. for a day it worked well but again user experienced the same issue.
What can be the possibility that is preventing the user not able to login, Its intermittent.