Just finished investigating and resolving an error whereby the message ‘Specified Port is Unknown’ appears when adding a network printer. This was first noticed when running a login script that add’s printers didn’t actually add any printers.
To fix this problem, you need to delete references to the printer drivers in the registry. I had already deleted any references to any network printers in an earlier attempt to fix the problem, so I wil;l include that as a step as it will not affect any functionality.
- Open Registry Editor, making sure that you have administrator rights.
- Expand HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Print\Environments\Architecture\Drivers\Version-3
- Delete any subkeys for printer drivers that have been installed.
- Expand HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\WindowsNT\CurrentVersion\Print\Printers
- Delete any subkeys that reference any network printers.
- Close Registry Editor
- Restart the Print Spooler services
After this had been completed, all of the shared printers as part of the login script connected and functioned as they should.
All I can imagine is that one of the drivers was corrupt, or information had not been removed from the registry when a printer was removed.