Management Center administrator logins to a page that does not exist. For example, when going to https://mc_ip:8082/test, it returns a 404 status code as seen below:
Release : 220.127.116.11
The 404 status code can happen (expected) soon after a reboot/restart of Management Center (MC). The Web UI will take more time to be available than the CLI soon after MC service is restarted. Further, there is a known issue with Web UI not starting up and returning a 404 status code, prior versions to 18.104.22.168. We have since fixed this issue by upgrading to MC version 22.214.171.124.
Also, when already logged in to MC version 126.96.36.199 and making another login attempt to a nonexistent page, for example https://mc_ip:8082/test , a 404 status page will be given to the administrator, informing the user that page doesn't exist. However, if you are logged out of MC and you enter a nonexistent URL, https://mc_ip:8082/test in the browser, MC will redirect the user to it's login page.