Microsoft has identified a rare bug where Windows 10 will cause issues with USB printers if they are connected to the PC when Windows is shutting down. It’s not a widespread issue as the circumstances of the bug makes it hard to replicate on a computer.

In a support document (via Bleeping Computer), Microsoft explains, “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.” Microsoft has listed the following as the cause of the problem:

  • 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.

Fortunately, you can easily mitigate the issue by connecting a powered-on USB printer before starting a device affected by this bug. Microsoft has confirmed that the issue affects all the editions of Windows 10 1903 and above. The company is working on a solution for the problem and will roll out a patch to fix the issue.

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