Server 2022: Sept/Oct 2026 CUs replace PS5UI.DLL/PSCRIPT5.DLL with 26100 builds, which breaks Type 3 print drivers (Event 808 0x7F, install error 0x8007078A)

Welcome to Microsoft Q&A!

Thank you for taking the time to provide such a detailed description of the issue and the troubleshooting you have already performed.

Based on the information currently published by Microsoft, I could not find this specific Type 3 printing failure documented as a known issue for KB5122882, KB5129237, or the October 2026 Windows Server 2022 updates.

Therefore, at this time, I cannot confirm through Microsoft Q&A whether the 26100-version PS5UI.DLL/PSCRIPT5.DLL files represent a servicing issue on Windows Server 2022, which ntprint.inf package is expected to be selected in this scenario, or whether Microsoft is planning a fix.

• Possible cause

The testing you have already completed provides useful diagnostic evidence and suggests that the issue may involve the shared Windows printing framework rather than being specific to one Adobe, HP, or DYMO driver.

In particular, the repeatable Event 808 failure while loading PS5UI.DLL, followed by the driver-installation failure, is an important observation. The 0x8007078A result corresponds to ERROR_KM_DRIVER_BLOCKED. An attempt to install a kernel-mode printer driver can fail with this error.

However, the currently public available Microsoft documentation does not establish that the updated PS5UI.DLL is causing Windows Server 2022 to classify these particular Type 3 drivers as kernel-mode drivers.

Similarly, the fact that restoring the earlier shared framework files restores printing is valuable troubleshooting evidence, but it does not by itself confirm that the 26100 files are incorrect for Windows Server 2022. Determining the expected component versions and why a particular ntprint.inf package is being selected requires validation of the Windows servicing state.

• Recommendation

Given the depth of troubleshooting you have already completed, I would not recommend continuing to manually replace PS5UI.DLL, PSCRIPT5.DLL, UNIDRV.DLL, UNIDRVUI.DLL, or UNIRES.DLL, or modifying the ntprint.inf package in DriverStore as a long-term solution.

These files are Windows-serviced printing components, and Microsoft has not currently public documented the file replacement you described as a supported workaround for this specific issue.

Since you already have a Microsoft Support case open, the safest next step is to continue working through that case rather than making further changes to the inbox printing components.

I recommend asking the support engineer to validate specifically:

Which ntprint.inf package and Pscript/Unidrv component versions are expected on Windows Server 2022 build 20348 after the September/October 2026 updates, and whether selection of the observed 26100 package is expected.

The Event 808/215 records, setupapi.dev.log entries, before-and-after file versions, DriverStore package versions, and your cross-driver reproduction results should be particularly useful evidence for that investigation.

• The reason why Microsoft Q&A cannot confirm this further

I also want to clarify why there is a limit to what we can reliably determine in Microsoft Q&A in this case.

Microsoft Q&A is a community technical forum. It is well suited to explaining documented Windows behavior, reviewing published known issues, and suggesting troubleshooting based on publicly available Microsoft documentation.

However, this case goes beyond normal configuration or driver troubleshooting. Confirming whether an unpublished Windows servicing regression exists, determining whether a specific inbox component or DriverStore package was incorrectly serviced to Windows Server 2022, confirming the internally expected package version, or determining whether Microsoft plans to release a servicing fix requires investigation by Microsoft Support and the relevant product/servicing teams.

Those conclusions cannot be established reliably from DLL version numbers or Event Viewer data alone, and forum contributors do not have the ability to validate Microsoft's internal servicing/package decisions or provide an officially supported replacement for Windows-serviced components.

For this reason, your existing Microsoft Support case is the appropriate path forward. If the investigation confirms that the observed package or component selection is not expected on Windows Server 2022, Microsoft Support can work with the appropriate engineering team to determine the supported remediation and track any required servicing correction.

I appreciate the thorough testing and evidence you have already collected. It should give the support team a strong starting point for validating the behavior.

References: Resolved issues in Windows Server 2022 | Microsoft Learn

September 8, 2026—KB5122882 (OS Build 20348.5622) | Microsoft Support

October 13, 2026—KB5126655 (OS Build 20348.5761) | Microsoft Support

Choose User Mode or Kernel Mode - Windows drivers | Microsoft Learn

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