Some .fnc files are plain text (ASCII), while others are compiled binary. If your system expects a binary file (machine code) and you feed it a text file (or vice versa), you will receive the 489 error. This often happens when a technician opens an FNC file in Notepad, accidentally adds a space, and saves it.
The error is most frequently triggered by syntax issues or hardware communication failures: Syntax & Formatting Errors 489 invalid fnc file
IR-2026-04-17-001 Date of Incident: [Insert date] Reported By: [Your name/team] System/Application: [System where error occurred] Affected File: 489.fnc (or filename as shown) accidentally adds a space