You get “Printer Subsystem is Unavailable” errors in Windows when you try to printer a document. This problem is known to have been caused by conflict between some HP printers and Adobe Acrobat Writer. This problem has been observed with HP laserjet 1020. The conflict corrupts the HP printer driver installed on your computer.
Because your computer is not able to load the corrupt printer driver, the print spooler service required for printing on your computer is stopped, and the list of installed printers on your computer will not be available.
Fix Printer Subsystem Is Unavailable Error Windows
To fix printer subsystem is unavailable error, Windows registry needs to be edited. Take great care when editing Windows registry any mistake may cause your computer to become unstable. Editing the registry requires that your computer account has administrative rights.
1. Stop the print spooler service
1.1 Click Start, click Run, and type services.msc in the Open field, click OK
1.3 The Print Spooler service may have been stopped already if the error has just occurred.
2. Open the Windows registry editor
2.1 Click Start, click Run, and type regedit in the Open field, click OK
2.2 Open the following registry key by expanding HKEY_LOCAL_MACHINE , expand System, expand CurrentControlSet, expand Control, expand Print, then click on Monitors
3. A subkey containing HP 1020 in the name should be available in the Monitor key. Right Click on the subkey, select delete, click OK to confirm delete.
4. Start the print spooler service by repeating Step 1, and select Start instead of Stop. You should now be able to see the printers on the computer
5. Reinstall the HP 1020 printer or any other printer that may have caused the Printer Subsystem is Unavailable error. Printer can be reinstalled by removing and replacing the printer USB cable on the computer. The printer will be detected again by Windows and automatically reinstalled. You may have to provide the correct driver or updated driver if requested by Windows.