Technical Tip: Local Admin username field does not allow invalid characters

After upgrading to v7.4.x onwards, Administrators will encounter an 'Input value is invalid' error when creating a local administrator user, using Invalid characters (i.e., dots '.') in the username field.

As an example scenario:

In the GUI, go to System -> Administrators -> Create new, then create a local admin with username 'test.admin' and select OK.

The following error is displayed, and the local admin user is not created.

In CLI, creating the local admin user gives the same error.

Solution: The problem will be resolved by following the rules below for the local admin username:

• Use only these characters: a-z, A-Z, 0-9, - , _.
• Cannot begin with -, and can end with $.

Notes:

• This behavior is enforced only when creating a new local administrator from v7.4.x onwards, but the existing admin users with special characters in the username will continue to function as normal unless that admin username is being modified using the special characters that are not allowed.
• Starting from FortiOS v7.4.5 and v7.6.1, dots ('.') are once again allowed; however, they cannot be used at the beginning of an admin username (i.e., '.admin' is disallowed, but 'test.admin' is allowed).