I had a client yesterday that had an HP Office Jet 9600 something or other and after upgrading from Windows 8 to 10 it indeed needed reinstalled. Printer object was there but showed an error that the driver was not available. Reinstalling the printer fixed it. First time I have ever needed to reinstall a printer driver from an 8 to 10 upgrade. Perhaps something in build 1903 changed the way it handles it, I have no idea.