What to do if ZKTeco IP Access Controllers show 'Access Denied (Unknown Format)'?
- BbrownthomasAug 1, 2025
If your ZKTeco IP Access Controller displays "Access Denied (Unknown Format)," it could mean that the D0 and D1 wiring are reversed. Another possibility is that the card type you swiped isn't recognized by the system. Check the card type and ensure it is compatible with the device.