Maximum number of users in the system reached

What causes this issue?

You attempted to log on at the system, but there are too many users.

System Response

The system issues an error message and will not allow you to continue with this transaction until the error is resolved.

How to fix this error?

Make sure that another user logs off so that you can work, or get a
corresponding licence from SAP AG.

Error message extract from SAP system. Copyright SAP SE.