Power Fx function
Errors and blanks
User
Identity of the current user.
What it does
The job: Detect missing values and failed operations before they break a formula at runtime.
How to use User
Start from the task, not the alphabet. If you are shaping rows for a gallery, reach for User alongside the other data functions in its group; if you are saving, navigating, or changing state, use it on an event such as a button OnSelect rather than in a display property. When a formula misbehaves, check for a blank value where you expected text, then confirm the behavior against the examples in the Power Fx function reference hub.
New to the language itself? Read What Is Microsoft Power Fx? first, then come back here when you need this specific tool.