If you are struggling to connect a USB printing to your Windows 10 PC and the USB printer port is no longer working or is simply invisible then Microsoft has an advice for you. In a support note, Microsoft has acknowledged that there is a problem where the USB printer port goes missing after disconnecting the printer while Windows 10 is shut down. The problem exists in Windows 10 version 1903 or later.
“If you connect a USB printer to Windows 10 version 1903 or later, then shut down Windows and disconnect or shut off the printer, when you start Windows again the USB printer port will not be available in the list of printer ports. Windows will not be able to complete any task that requires that port,” explained Microsoft in its support page.
To see the list of printer ports go to Start > Settings (gear icon) > Devices > Printers & Scanners > Print Server Properties > Port tab.
If you are facing this problem, then the easiest way to solve the issue is to connect a powered-on USB printer before starting Windows.
Explaining the technical reason for this glitch, Microsoft said, If the driver for the USB printer contains a Language Monitor, the OpenPortEx callback function of the Language Monitor would not be called. As a result, the user cannot fulfill operations dependent on the operation of the Language Monitor. In the “Devices and Printers” control panel, when selecting [Print Server Properties] > [Port] tab, the port for the USB printer (such as “USB001”) would not appear in the list of printer ports. As a result, the user cannot fulfill operations dependent on the existence of the port.”