Microsoft released updates for Windows 10 on June 9, 2020. This means that USB and network printers can no longer print in some cases.
Users of Windows 10 clients and administrators of the Windows server counterparts are currently suffering from two different printer problems that were caused by bugs.
The first bug prevents USB printers from being recognized at all from Windows 10 version 1903. The error always occurs when a USB printer is switched off or offline, and Windows 10 is then shut down.
When Windows is restarted, the operating system is no longer able to recognize the printer. This is then missing from the list of printer ports. The solution to this problem is to turn on the printer and restart Windows 10.
In the meantime, optional, manual updates for all Windows versions still in support have been released. The correction updates are (if they prove to be effective on the respective target system) to be preferred to the workarounds from this article.
Further information and download links are available here:
June 2020 security updates block printers
Regardless, there is another printer problem caused by the June 2020 updates. Shortly after the patch day on June 9, 2020, there were numerous user reports that printers were no longer available. It quickly became apparent that uninstalling the latest update would fix the printing problem as a first workaround.
Microsoft has now confirmed this problem on the Windows 10 Version 2004 status page. As a result, certain printers may no longer be able to print after installing cumulative update KB4557957.
In affected systems, the print spooler will print an error or close unexpectedly. This means that nothing is output on the affected printer. Printing from applications, including to PDF printers or the like, is no longer possible.