A user receives an error message that their username or password is invalid. What should the administrator do FIRST to address the issue?

The most appropriate first step for the administrator to address the issue of invalid username or password error messages is to learn of any recent changes to the system. This is crucial because recently implemented changes could directly impact user authentication. Changes may include updates to user account settings, a reset of user passwords, or modifications to the authentication system itself.

Understanding what modifications were made before the error occurred allows the administrator to identify if the issue is caused by those changes. For example, if a password policy was altered, it might require users to meet new criteria that the affected user has not considered.

Attempting to replicate the issue is important, but it typically comes after gathering relevant information about recent changes. Knowing the context of any modifications helps shape the testing and resolution efforts. Installing OS patches or restoring the system should only be considered if there is clear evidence that those actions are required, as they might not pertain directly to the username or password issue at hand.