Forum Discussion
Is this the Microsoft Windows Application Compatibility fix Database?
My Windows 11 25H2 laptop has an application called "Microsoft Windows Application Compatibility fix Database" that inexplicably appeared in "Settings" → "Applications". It was installed around 4 PM today; I didn't click on any applications, it just suddenly appeared. Does anyone know what this application is? Its location is C:\Windows\AppPatch, and the modification date has also changed.
10 Replies
That's a legit built-in Windows component - it is part of the Application Compatibility (Shim) infrastructure that stores compatibility fixes for older apps, not malware. It seems that it got triggered/registered by a recent cumulative update or a compatibility database refresh, which is probably why you saw a new timestamp around 4 PM.
MS needs to consider not naming the SDB {22221111-1111-1111-1111-111111111111}.sdb as this sets of alerts if you dig into it as it's often used for testing and looks very suspicious
This entry is a legitimate Microsoft-issued compatibility shim database, delivered via Windows Update out-of-band (not through a normal cumulative update).
It's tied to a specific fix Microsoft has been pushing out in late August 2026: the inpoutx64.sys driver — used by a lot of RGB lighting/peripheral software.
yeah but it caused more issues by having it, since deleting it... it is running as normal.
Just spent several hours digging into the sdb and associated entries that were added, only to find this article noting the hotfix for the Arc Raider crashes.
SentinelOne flagged this in our system, so we had to investigate. The registry entries were suspicious, and the .sdb file creation was suspicious.I learned a lot about the .sdb file type and the associated registry entries.
Darn you Microslop.
Since this "hotfix" its messed up all my browser log ins - thanks for this!
This a new hotfix rolling out to fix driver issues caused by the August 2026 Monthly Update, if you have specific games which depend on the inpoutx64.sys driver.
Resolution: This issue is resolved by a block that prevents the inpoutx64 driver from loading. The block targets devices with this specific driver enabled and the game ARC Raiders installed. This resolution disables the inpoutx64 driver and displays a message window with information about the disablement. Following this message, the game will launch as normal.
This resolution is propagating automatically to Windows consumer and business devices that are not managed by IT departments, and a device restart is required. Please note that it might take up to 24 hours starting from August 26, 2026, 6 PM PT for this resolution to reach all affected devices. The driver block will also be included in the September 2026 Windows security updates and subsequent releases.
My laptop uses Windows 11 25H2. Before installing KB5101684, the file history functioned correctly. In "Control Panel → All Console Items → File History," the "Last Backup" time was updated correctly whenever a file was successfully backed up to the D: drive.
However, after installing KB5101684 on July 29, 2026, problems began to occur:
Files can still be backed up to the D: drive normally.
The "Last Backup" time in "File History" fails to update correctly.
Newly created or saved Word documents, images, videos, etc., still show "No previous version available" in "Properties → Previous Versions."
Even more worryingly, my Windows 10 22H2 desktop computer also started experiencing similar file history synchronization issues after installing KB5120249 on August 12, 2026.
Those bugs were introduced by the August 2026 Update, and have nothing to do with "Microsoft Windows Application Compatibility Fix Database". If you remove this app, it will not fix your File History problem which other users have also reported as broken after installing Aug 2026.
You can uninstall the last Monthly Update, or wait for MS to fix the problems.
interesting, it had also appeared to me.
I uninstalled it - no idea what it is.
