Troubleshooting Tip: Getting 'Registration Attempt by Endpoint [] was denied due to Local authentication failure for user "0xc00xxxxxxx" Server' log message in FortiClient EMS

This issue may happen when performing local user authentication user onboarding to FortiClient EMS.

Issue symptoms:

1. In FortiClient, after entering username + password, FortiClient re-prompts the login window again.
2. In EMS -> Administration -> Log Viewer, the log message 'Registration Attempt by Endpoint [] was denied due to Local authentication failure for user "0xc00xxxxxxx"' will appear.

To resolve this,

1. Go to EMS -> User Management -> Local Users -> Select -> Delete the affected user.
2. Create a new local user (can use the same username) and save the configuration.
3. In the endpoint FortiClient, log in with the new local user credentials.

In this way, FortiClient should be able to join EMS and become an authorized user.