The PrintNightmare vulnerability that left Windows systems vulnerable to attacks has been patched, but the update introduces a new issue for certain types of printers.

Microsoft says that the KB5004945 patch for the PrintNightmare exploit, which is caused by a vulnerability in Windows Print Spooler, works as intended. However, some users are now reporting that the security update is causing connection errors with their printers, specifically Zebra label printers. Microsoft says that the connection errors are a result of changes in the overall update and are not part of the PrintNightmare fix.

"Our research has shown that the OOB security update works as intended and is effective against the known printer spooling exploits and other publicly reported vulnerabilities collectively referred to as PrintNightmare," Microsoft wrote in its blog update. "All of the reports we investigated involved changing the default registry setting related to Point and Print to an unsafe configuration."

In a statement to The Verge, Zebra advises uninstalling the KB5004945 update until the company can release its own update.