Signature verification failed #26606 (MK4S) #13606 (MK4) #21606 (MK3.9) #23606 (MK3.5)

Relevant for:

MK4 MK3.9 MK3.5 MK4S

Last updated 4 months ago

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What happened?

When trying to install non-official firmware on your Original Prusa MK4, MK3.9, or MK3.5, the screen shows "Firmware signature verification failed! Only official signed firmware can be flashed".

Error name: Signature verification failed

Error code: #26606 (MK4S) #13606 (MK4) #21606 (MK3.9) #23606 (MK3.5)

The error is issued when your printer has detected an attempt to flash firmware that does not have the private key signature that verifies the firmware as being official.

How to fix it?

The Original Prusa MK4, MK3.9, and MK3.5 in their factory state only accept official firmware. In order to flash a custom firmware, you need to break the appendix on the xBuddy board.

Breaking the appendix on the mainboard of the Prusa MK4, MK3.9, and MK3.5 is IRREVERSIBLE and leads to VOIDING OF THE WARRANTY ON ELECTRONIC PARTS OF THE PRINTER.
If you break the appendix, we disclaim any responsibility for any damage to the printer and/or its surroundings (e.g. in case of a fire).

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