The first three characters must not be part of the user name

What causes this issue?

The first 3 characters of the password must not occur in this sequence
in the user ID. This is intended to prevent user IDs and passwords
being identical.

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?

Choose another password.

Error message extract from SAP system. Copyright SAP SE.