Printer GPO – Fix ‘hr = 0x80070706 The Print Processor is Unknown’ Error

See: Print Processor

Either the default print processor is missing or corrupt (KB153355) or that driver you are trying to install with that print queue requires its own print processor that is unavailable on your client machine. This can be caused for a number of reasons, but in my experience it is most commonly a 32-bit/64-bit mismatch or you are missing the driver's specific print processor. I generally unpack print drivers that come in .EXEs using 7Zip, locate the appropriate DLLs and the .INF file to avoid installing all the other packaged crap that comes with print drivers these days. Unfortunately, this method of manual driver installation will not install that drivers print processor and not all drivers can use the default Windows print processor.

You can use Print Management to see what drivers are available and what print processor you are using. Verify that the print processor is available on the client. Try attaching ProcMon to the spoolsv.exe on your client and manually add the printer. Printing Services errors are notoriously vague and misleading. Looking at the logs in Microsoft-Windows-PrintService should help you narrow your search in ProcMon, as often Windows will log what .DLL from the driver failed to find the print processor.