Description
You may get this error message in the Quartus® Prime software if you attempt to program an encrypted .pof into a MAX 10 device multiple times after the Encrypted Key Programming (.ekp) file has been programmed.
This is because you can only program the encrypted .pof file into a MAX® 10 device once after the .ekp file has been programmed.
Resolution
If you want to program a new encrypted .pof file into the MAX 10 device, you need to fully erase the device first, program the .ekp file and then program the encrypted .pof file.