USB printer port missing after disconnecting printer while Windows 10 (version 1903 or later) is shut down

Applies to: Windows 10, version 1903, all editionsWindows 10, version 1909, all editionsWindows 10, version 2004, all editions

Symptoms


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.

The list of printer ports can be found at: Start > Settings (gear icon) > Devices > Printers & Scanners > Print Server Properties > Port tab.

Cause


  • 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.

Resolution


You can avoid the issue by connecting a powered-on USB printer before starting Windows.

More information


Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section. We are working to fix the issue in a future version of the operating system.

For developers and hardware vendors: to get more information on Print Monitors, Language Monitors and OpenPortEx function, see the following documents -

Writing a Print Monitor

Language Monitors

pfnOpenPortEx callback function