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Nancy CampbellSep 5, 2025
What does 'Unusable Device' mean on my Brother MFC-8520DN All in One Printer?
- CCarl JacksonSep 5, 2025
The 'Unusable Device' error on your Brother All in One Printer indicates that a defective USB device or a high power consumption USB device has been connected to the USB direct interface, or a USB device or USB Flash memory drive that is not supported/is encrypted has been connected to the USB direct interface. Unplug the device from the USB direct interface and turn the machine off and then on again.