Windows 10 printer problems: This bug makes USB printer ports vanish, says Microsoft

Microsoft promises fix for Windows 10 glitch that can cause USB printer ports to become unavailable.

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Microsoft has detailed a potentially frustrating Windows 10 glitch affecting PCs with a printer connected via a USB port. 

The issue, which affects Windows 10 version 1903 and newer, can happen when users connect a printer via USB and 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," Microsoft said in a new support note

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For now, Microsoft recommends connecting a powered-on USB printer before starting Windows to avoid the issue, but it is planning to release a Windows update in future that fixes the problem. 

Microsoft lists two main causes for the issue that cause the USB printer port to become unavailable for carrying out printer tasks. 

"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," it explains. 

"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."

Those very specific conditions for reproducing the bug make it unlikely that most Windows users would experience the glitch.   

June has been a busy month for Microsoft in terms of addressing bugs. The June 2020 Patch Tuesday was its biggest ever, containing fixes for 129 vulnerabilities. The Windows 10 2004 rollout has been hampered by several unresolved incompatibility issues affecting Intel, Nvidia and Realtek drivers.  

Earlier this week it also released a fix for a bug that prompted it to block the Windows 10 2004 update for multiple Surface devices.

And it confirmed a Windows 10 2004 bug was causing external displays to go black when users draw within Office apps.  

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Microsoft yesterday said it would now gradually start throttling up availability of Windows 10 2004 to more users, but it appears to be approaching the rollout cautiously.    

ZDNet's Mary Jo Foley reported yesterday that Microsoft is expanding the group that will have the Windows Feature Experience Pack installed on their Windows 10 2004 machines. 

Curiously, Microsoft hasn't divulged what the pack is for, but it looks like it has bundled some core features and apps so they can be updated via the Microsoft Store at a faster clip than updates through the Windows OS.