Microsoft Confirms Two August 2026 Windows Update Bugs

Microsoft has confirmed two distinct regressions linked to its August 11, 2026 Patch Tuesday updates. One affects certain games on Windows 11 24H2 and 25H2 when RGB-capable hardware has software or drivers with names similar to inpoutx64. The other affects some Windows Presentation Foundation (WPF) applications that print or generate PDF/XPS content using particular fonts. 2223

Neither issue had a permanent-fix timeline in Microsoft’s published guidance. Both remained under investigation, so the available mitigations should be treated as temporary. 122223

1. Windows 11 games can crash when an RGB-related driver is present

After the August 11 update KB5121003 and later updates, Microsoft received reports that some games would not run as expected on Windows 11 24H2 and 25H2. The games named in Microsoft’s release-health notices include ARC Raiders, MARVEL Tōkon: Fighting Souls, and THE FINALS. 2223

Microsoft’s ongoing investigation linked the failures to peripherals or internal components with RGB lighting features. These devices may install drivers or code components with filenames similar to inpoutx64. Reported symptoms include freezes, game closures, EXCEPTION_ACCESS_VIOLATION errors, and, in some cases, a system restart. 2223

Microsoft’s temporary gaming workaround

Microsoft’s workaround is to temporarily disable the inpoutx64 driver in the Windows Registry:

1. Back up the Registry before making any changes.
2. Open Registry Editor.
3. Go to HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\inpoutx64.
4. Set the Start value to 4.
5. Restart Windows. 2122

This does not fix the underlying compatibility problem. It prevents the driver from starting while Microsoft investigates the interaction between the RGB-related component and the affected games. 2223

The trade-off for gamers

Disabling the driver may stop RGB lighting or the vendor software that controls it from working. Keep a record of the original Registry value so the driver can be re-enabled later, and avoid editing the Registry without a backup. Microsoft has not provided a permanent-fix date. 2122

2. WPF applications can fail when printing or creating PDFs

The second regression comes from the August .NET Framework cumulative updates. Some WPF applications can throw a System.IO.FileFormatException when printing or generating PDF/XPS content that uses certain fonts, including Calibri. Microsoft’s support documentation identifies the issue across affected supported Windows client and Server releases. 12

The failure occurs in the WPF font-processing path, rather than representing a general failure of every Windows printer or PDF workflow. Reports identify Calibri, Cambria, Constantia, and Corbel among the fonts that can trigger the problem, although Microsoft’s official notices specifically name Calibri. 123

Developer workaround for WPF applications

Application developers can add this AppContext switch to the affected application’s configuration file:

<configuration>
  <runtime>
    <AppContextSwitchOverrides value="Switch.MS.Internal.TtfDelta.DisableCmapAndSbitOverflowProtection=true" />
  </runtime>
</configuration>

Microsoft documents the switch as a mitigation for the System.IO.FileFormatException encountered during printing or PDF/XPS generation. 12

Why the WPF workaround carries security risk

The switch disables the CMap/SBit overflow protection introduced by the security update. That means it may restore output for an affected application, but it also weakens the relevant font-processing protection. It should therefore be used only as a temporary, controlled measure while the application owner evaluates the risk and waits for Microsoft’s fix. 3

A less security-sensitive option is to keep the protection enabled and avoid the triggering fonts when the document or application allows it. Reports from Microsoft’s Q&A community indicate that substituting fonts such as Arial or Times New Roman can restore printing or XPS output in some cases, but this is not guaranteed for every application or document. 910

What users and administrators should take away

• The gaming and WPF failures are separate update regressions, not one combined Windows problem.
• Gamers should check for RGB hardware software or components containing an inpoutx64-like driver before removing a Windows update.
• Disabling that driver can sacrifice RGB functionality, and Registry changes should be backed up first. 2122
• WPF application developers should understand that the AppContext workaround disables a security protection.
• Font substitution or a different output path may avoid the WPF failure without disabling that protection, but compatibility must be tested. 3910
• Microsoft was still investigating both issues and had not announced a permanent-fix date in the cited guidance. 122223