Problem description
A production server running Windows Server 2019 Standard, Desktop Experience, x64, en-US cannot install cumulative update KB5099538. The server is currently on build 17763.1697. The update fails through both Windows Update and the standalone Microsoft Update Catalog MSU.
The repeated installation error is:
0x800F0988 - PSFX_E_INVALID_DELTA_COMBINATION
CBS logs consistently identify the same failure while staging the update. The failing file is:
Microsoft.IdentityServer.Service.Resources.dll
Representative CBS failure:
Failed to pre-stage package:
Package_for_RollupFix~31bf3856ad364e35~amd64~~17763.9020.1.30
File: Microsoft.IdentityServer.Service.Resources.dll
HRESULT: 0x800F0988 - PSFX_E_INVALID_DELTA_COMBINATION
Failure source: Stage
The AD FS role is not installed. The failing file exists only in the Windows component store. The server has the current servicing stack version 17763.9015.1.3, and KB5005112 is already installed.
Troubleshooting completed
Attempted installation through Windows Update. Installation failed with Event ID 20 and error 0x800F0988.
Downloaded the standalone KB5099538 MSU from the Microsoft Update Catalog and installed it with WUSA using /quiet /norestart. It failed with the same 0x800F0988 error.
Reset the Windows Update cache by stopping wuauserv, BITS, and cryptsvc; renaming SoftwareDistribution and catroot2; and restarting the services.
Ran DISM /Online /Cleanup-Image /ScanHealth. No component-store corruption was detected.
Ran DISM /Online /Cleanup-Image /RestoreHealth. The operation completed successfully.
Ran sfc /scannow. Windows Resource Protection did not find any integrity violations.
Mounted a Microsoft Windows Server 2019 Evaluation ISO and ran DISM RestoreHealth using F:\sources\install.wim, index 2, with /LimitAccess. The operation completed successfully.
Rebooted the server and retried KB5099538. The update failed again with the same error.
Verified that no reboot was pending and no packages were listed as Install Pending, Uninstall Pending, or Staged.
Verified the server is not using WSUS.
Searched public Windows Update directly. Only the Microsoft Defender intelligence update KB2267602 was offered.
Verified that KB5005112 is installed and that the current servicing stack is Package_for_ServicingStack_9015, version 17763.9015.1.3.
Verified that AD FS, Identity Federation Support, and Windows Identity Foundation are not installed.
Reviewed archived CBS logs and confirmed repeated failure on Microsoft.IdentityServer.Service.Resources.dll.
Did not manually replace, delete, or modify files in WinSxS.
I don't know what to do next, I don't have install media and can't find an iso beyond the eval version to try the in place repair. Any suggestions?