If you are logged into a Controller UI session with an account other than the root user, log out or open a new browser window in private (incognito) mode. If you do not, you will get an "Access Denied" error when you attempt to open the console page.
In the browser enter the URL of the Administration Console:
The console is served on the same port as the Controller UI, port 8090 by default.
Log into the system account with the root user password. The root user is a built-in global administrator for the Controller. Use the password you set for this user when installing. For more information on root and other types of administrative users, see User Management.
The root user password is different from a normal AppDynamics account password. It is not the same as the account owner or account administrator password. If you are logged into the Controller using your current account, you need to log out of that account and then back in as the root user to access the admin console.
For information on changing the Controller root user password, see User Management.