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[BUG] Windows Server 2025: cumulative update KB5094125 (OS build 26100.32995) breaks MSIX registration — package lands "Modified, NeedsRemediation" despite deployment reporting success; removing the LCU fixes it #70700

Description

@erngab

Preflight Checklist

  • I have searched existing issues and this hasn't been reported yet
  • This is a single bug report (please file separate reports for different bugs)
  • I am using the latest version of Claude Code

What's Wrong?

Claude Desktop (MSIX, package family Claude_pzs8sxrjxfjjc) ran fine for months on Windows Server 2025. It broke immediately after a Windows Update + reboot on 2026-06-19. Only Windows changed — Claude itself was not updated.

After the update, every install either fails with AddPackage failed: AddPackage failed with HRESULT 0x80073CF6, or "completes" and the package immediately shows Status: Modified, NeedsRemediation with PackageUserInformation : {} (registered for no user) — even though the AppX deployment operational log reports the Register operation finished successfully (Event ID 400, 0x0).

Verified cause: the June 9, 2026 OS cumulative update KB5094125 (OS build 26100.32995). The three packages installed on 2026-06-19 map to:

  • Package_for_RollupFix31bf3856ad364e35amd64~~26100.32995.1.21 → KB5094125 (the OS LCU) ← the one that needed removal
  • Package_for_ServicingStack_32985~...~26100.32985.1.4 → KB5094137 (SSU) — left intact
  • Package_for_DotNetRollup_481~...~10.0.9335.3 → KB5087051 (.NET, May 2026) — left intact, NOT the cause

Environment: Windows Server 2025 (Evaluation), build 10.0.26100.32995, x64, KVM guest (netcup VPS). Standard user with UAC elevation; built-in Administrator disabled. Microsoft Store present; non-MSIX .exe apps install fine, so the failure is specific to MSIX registration.

What did NOT durably fix it: Remove-AppxPackage + fresh install, Add-AppxPackage -Register, Reset-AppxPackage, DISM /RestoreHealth + sfc /scannow (helped once then the failure returned after reboot, SFC then clean), disabling CoworkVMService (Set-Service "Access is denied"; registry Start=4 reverts to 2 on boot; IFEO on cowork-svc.exe). Orphan MSIX folders, EFS and AV all excluded.

What fixed it (durable across reboots):
Get-AppxPackage Claude | Remove-AppxPackage
Remove-WindowsPackage -Online -PackageName "Package_for_RollupFix31bf3856ad364e35amd64~~26100.32995.1.21" -NoRestart
Restart-Computer -Force
(then reinstall Claude with a fresh installer → Status: Ok, survives reboot)

Related: #68792 (same 0x80073CF6 "worked days ago", no cause identified), #37443 (Windows Update flipped a working MSIX install, DISM/SFC not durable), #49655 / #48003 / #49917 (CoworkVMService lock cluster — distinct here, since deployment succeeds yet package is NeedsRemediation and stopping Cowork didn't help).

What Should Happen?

A Windows cumulative update should not break MSIX registration for a previously-working app. The installer should also detect the post-install "Modified, NeedsRemediation" / "PackageUserInformation : {}" state and surface it instead of treating deployment 0x0 as success. Please test the MSIX deployment path against Windows Server 2025 at build 26100.32995 (KB5094125).

Error Messages/Logs

AddPackage failed: AddPackage failed with HRESULT 0x80073CF6
Get-AppxPackage *Claude*  →  Status: Modified, NeedsRemediation
PackageUserInformation : {}
AppXDeploymentServer/Operational Event ID 400: Deployment Register operation ... finished successfully (0x0)

Steps to Reproduce

  1. Windows Server 2025 with a working Claude Desktop MSIX install (Claude_pzs8sxrjxfjjc)
  2. Install the June 9, 2026 cumulative update KB5094125 (OS build 26100.32995) + reboot
  3. Launch Claude Desktop → "go to advanced options ... select Repair ... reinstall ... contact administrator"
  4. Uninstall and reinstall with a fresh installer → install reports success but the package is immediately Modified, NeedsRemediation, or AddPackage fails with 0x80073CF6

Claude Model

None

Is this a regression?

Yes, this worked in a previous version

Last Working Version

Worked for months until KB5094125 (2026-06-19)

Claude Code Version

N/A — this is a Claude Desktop (MSIX) issue, not Claude Code CLI. claude --version is not applicable (Claude Code is not installed). Affected package: Claude_pzs8sxrjxfjjc (Claude Desktop), build/version unknown because install/registration fails before the app launches reliably.

Platform

Anthropic API

Operating System

Windows

Terminal/Shell

PowerShell

Additional Information

Server 2025 Release Health does not list a known MSIX-registration issue for KB5094125. The fix here is removing the LCU (Remove-WindowsPackage) + reboot + fresh install; Windows Update was then paused to stop the KB returning. Caveat: removing the LCU reliably restores registration, but this may be an interaction between the new June servicing baseline and the MSIX deployment of a package that declares a packaged Windows service (CoworkVMService), rather than a bug in the KB alone.

Activity

  1. github-actions commented on Jun 25, 2026

    @github-actions

    Found 1 possible duplicate issue:

    1. [BUG] error code 0x80073CF6 for Claude Desktop with Cowork on Windows 11. #68792

    This issue will be automatically closed as a duplicate in 3 days.

    • If your issue is a duplicate, please close it and 👍 the existing issue instead
    • To prevent auto-closure, add a comment or 👎 this comment

    🤖 Generated with Claude Code

  2. erngab commented on Jun 25, 2026

    @erngab
    Author

    Not a duplicate of #68792 — same HRESULT, but this report adds the specific trigger (cumulative update KB5094125 / OS build 26100.32995), confirms it on Windows Server 2025, and provides a verified fix (Remove-WindowsPackage of the LCU). #68792 has neither a root cause nor a fix.

  3. changed the title [-][BUG] [BUG] Windows Server 2025: cumulative update KB5094125 (OS build 26100.32995) breaks MSIX registration — package lands "Modified, NeedsRemediation" despite deployment reporting success; removing the LCU fixes it[/-] [+][BUG] Windows Server 2025: cumulative update KB5094125 (OS build 26100.32995) breaks MSIX registration — package lands "Modified, NeedsRemediation" despite deployment reporting success; removing the LCU fixes it[/+] on Jun 25, 2026
  4. vucko211212 commented on Jul 23, 2026

    @vucko211212

    Claude Desktop MSIX: recurring NeedsRemediation caused by Code Integrity blocking vk_swiftshader.dll (package ships no CodeIntegrity.cat)

    Prepared: 2026-07-23. For: Anthropic support ticket + comment on github.com//issues/70700

    Environment

    • Windows 11 Pro 25H2, build 26200 (desktop machine, NOT Windows Server)
    • NOT MDM-managed (no Intune/SCCM), single user, per-user install via official MSIX
    • Package: Claude_1.24012.1.0_x64__pzs8sxrjxfjjc
    • Windows Defender only, zero threat detections in the relevant period (verified twice)

    Symptom

    Claude Desktop package repeatedly enters Status: Modified, NeedsRemediation
    (PackageStatus = 2 under HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\AppModel\StateChange\PackageList\<PackageFullName>,
    BinaryName = app\vk_swiftshader.dll). App then fails at GPU process init
    (GPU process gone, exitCode: 101457950 in main.log), CoworkVMService cannot start
    (sc start returns error 87, "The parameter is incorrect").

    Every known workaround is temporary: Settings Repair/Reset, setting PackageStatus = 0
    plus reboot, and two full uninstall/reinstall cycles all worked for a few hours, then the
    package was flagged again. On 2026-07-22 the package was flagged 4 separate times.

    Root cause evidence (Microsoft-Windows-CodeIntegrity/Operational log)

    Each incident is preceded by exactly this event cluster, with claude.exe as the loading process:

    Event 3010 (Warning, x3):
    Code Integrity was unable to load the \Device\HarddiskVolume3\Program Files\WindowsApps\
    Claude_1.24012.1.0_x64__pzs8sxrjxfjjc\AppxMetadata\CodeIntegrity.cat catalog.
    Status 0xC000003A.
    
    Event 3033 (Error):
    Code Integrity determined that a process (...\WindowsApps\Claude_1.24012.1.0_x64__pzs8sxrjxfjjc\app\claude.exe)
    attempted to load ...\WindowsApps\Claude_1.24012.1.0_x64__pzs8sxrjxfjjc\app\vk_swiftshader.dll
    that did not meet the Microsoft signing level requirements.
    

    Occurrences on 2026-07-22: 15:20:09, 18:19:40, 18:27:21, 23:31:35. The 23:31 cluster is the
    only Claude-related event of any kind between a healthy check at 19:23 and the package being
    found flagged at 09:00 next morning. In that overnight window there were: no AppX deployment
    operations, no Windows updates (nothing installed after 2026-07-16), no reboots, no power
    events, no NTFS errors, no Defender detections. The Code Integrity block is the only candidate
    trigger, and BinaryName in the StateChange registry key points at the exact same DLL.

    Key facts:

    1. The package does not contain AppxMetadata\CodeIntegrity.cat at all. The folder
      AppxMetadata does not exist even in a freshly downloaded and installed MSIX
      (package root contains only: app, assets, AppxBlockMap.xml, AppxManifest.xml,
      AppxSignature.p7x, priconfig.xml, resources.pri, resources.scale-200.pri).
      Status 0xC000003A in Event 3010 is simply "path not found".
    2. vk_swiftshader.dll is NOT corrupted or tampered with. Get-AuthenticodeSignature
      returns Valid, signed by CN="Anthropic, PBC". The "Modified" package state is a false
      positive from Windows' perspective of the failed signing-level check, not actual tampering.
    3. The trigger is sporadic because vk_swiftshader.dll is only loaded when the Electron GPU
      process falls back to the SwiftShader software renderer. That is why the package can
      survive many launches and then suddenly get flagged, and why every repair holds only
      until the next fallback.
    4. Control case: Google Chrome on the same machine logs the identical Event 3033 for its own
      vk_swiftshader.dll several times a day with zero consequences, because Chrome is not MSIX
      so there is no package for Windows to flag. This strongly suggests the bug is in the MSIX
      packaging (missing code integrity catalog for a DLL that gets loaded under a
      Microsoft-signing-level Code Integrity Guard mitigation), not in the machine.

    Suggested fix directions (for the Claude Desktop team)

    • Ship AppxMetadata\CodeIntegrity.cat in the MSIX so catalog validation of
      vk_swiftshader.dll (and other Electron DLLs loaded under CIG) can succeed, or
    • Relax/adjust the CIG (MicrosoftSignedOnly) mitigation on the GPU process for the MSIX
      build, or otherwise prevent a SwiftShader fallback from poisoning the whole package state.

    Relation to issue #70700

    Same package family, same Modified, NeedsRemediation status, same "works for months then
    suddenly breaks" pattern. This report adds: Windows 11 desktop (not Server 2025), no MDM,
    no Windows update correlation, and a concrete reproducible trigger (CI Events 3010+3033 on
    vk_swiftshader.dll with the catalog file absent from the package). The LCU-removal fix from
    that issue does not apply here: no cumulative update was installed in the failure window.

  5. erngab commented on Jul 27, 2026

    @erngab
    Author

    Update: July 2026 cumulative updates do NOT reproduce the issue

    After the Windows Update pause expired, the server installed the July 2026 updates on 2026-07-27:

    • KB5099536 (Security Update, OS build 26100.33158)
    • KB5100998 (.NET Framework Security Update)

    Claude Desktop works normally after reboot with these July updates installed. The Modified, NeedsRemediation issue from the June baseline (KB5094125 / build 26100.32995) does not recur.

    This confirms the problem was specific to the June cumulative update. The workaround (removing that LCU) is no longer needed — the July updates work cleanly.

    Regarding @vucko211212's Code Integrity root-cause analysis: I checked Microsoft-Windows-CodeIntegrity/Operational on my server — the only Event 3033 entries are from Google Chrome loading its own vk_swiftshader.dll. No Claude-related CI events were found. This does not rule out the same root cause (the relevant events from the June period may have rotated out after the LCU removal and reboot), but I cannot confirm it either.

  6. kevinandjacy-pixel commented on Aug 4, 2026

    @kevinandjacy-pixel

    Additional data point for #70700 — Windows 11 25H2 (Build 26200.8973), consumer SKU

    Same failure mode as reported in #70700, but on a different Windows branch and a different LCU, which suggests the problem is broader than Windows Server 2025 / KB5094125.

    Environment

    OS Windows 11 Home 25H2, Build 26200.8973
    Claude Desktop 1.24012.11.0 (MSIX, Claude_pzs8sxrjxfjjc, SignatureKind: Developer)
    Recent LCUs KB5101711, KB5101684 (installed 2026-07-29)
    Install method Official installer (not Store)

    Symptom

    Package spontaneously transitions from Ok to Modified, NeedsRemediation, after which Windows blocks activation ("無法開啟此應用程式 / This app can't open — go to Advanced options and select Repair") and/or force-closes the running app mid-session. Windows auto-repair then re-adds the package, clearing the flag temporarily, and the cycle repeats.

    Occurred 6 times in ~3 hours on 2026-08-04 between 17:52 and 20:36 local time.

    Key finding: the flag is set with no file changes and no deployment activity

    A polling watcher (15 s interval) captured a transition live:

    20:35:54  STATUS CHANGE: Ok -> Modified, NeedsRemediation
      AppX deployment events in prior 6 min : NONE
      AppModel status events in prior 6 min : NONE
      Package files modified in last 10 min : NONE
      Defender detections                   : NONE
      Package processes alive               : NONE
      Preceding signals:
        20:34:41  Kernel-Power 566: system session transitioned 7 -> 9
        20:35:47  DCOM 10016: activation denied for CLSID {2593F8B9-4EAF-457C-B68A-50F6B8EA6B54}
                  APPID {15C20B67-12E7-4BB6-92BB-7AFF07997402} running in application container
                  Claude_1.24012.11.0_x64__pzs8sxrjxfjjc
    

    The package contents are provably unmodified, so this appears to be the runtime integrity validation (AppxBlockMap.xml / AppxSignature.p7x chain) failing spuriously rather than actual package tampering.

    Onset correlates with a deferred-registration self-update

    00:56:35  Add operation, Claude-<hash>.msix
              Options: NormalPriorityRequest, DeferRegistrationWhenPackagesAreInUse
              (1.24012.9.0 -> 1.24012.11.0 while the old version was running)
    00:56:42  New package status 0x80000; old package 0x200000 (registration pending)
    09:15:54  RegisterByPackageFamilyName (ForceTargetApplicationShutdown,
              SkipReregisterIfPackageStatusOk) -> status 0x0, clean
              [app used normally for ~8 hours, no issues]
    17:31:17  AppX container destroyed (app closed)
    17:52:20  status already 0x2  <-- flag appeared silently, no deployment events in between
    

    Every subsequent repair attempt produced the same triad:

    Id=419  0x80073D02: Unable to install because the following apps need to be closed
    Id=8107 Illegal non-AppStore or non-AppInstaller package integrity validation
            attempted for package <PKG>. Flags: 0x0
    Id=8104 Failed to set the Trust Label on package <PKG> with flags 0x0. Error: 0x80070057
    

    Ruled out on this machine (with evidence)

    Hypothesis Result
    Smart App Control interference Ruled out — VerifiedAndReputablePolicyState = 0 (off)
    Package files tampered / disk corruption Ruled out — zero file changes at flag time; no NTFS/disk errors on C: in 7 days
    Defender quarantine Ruled out — zero detections
    Auto-updater installing in a loop Ruled out — updater logs only "Checking for updates", never downloads
    Leftover claude.exe processes blocking registration Insufficient — cleared all processes, registered cleanly to Ok, flag returned ~15 min later
    CoworkVMService pinning the package Not the cause — SCM 7034 "Claude service terminated unexpectedly" fires after the package enters remediation, i.e. it is a consequence. Matches #70700's finding that disabling the service does not help
    Fresh reinstall from a newly downloaded installer Does not fix it — reinstalled 19:00:02 (ForceApplicationShutdownOption, ForceUpdateFromAnyVersion), package was flagged again by 19:26
    Repair (Settings > Apps > Advanced options > Repair) Temporary only — clears the flag, returns within ~15-30 min
    Reset Temporary and destructive — wiped local app data including sidebar session-group assignments (dframe-store.customGroupsByScope[].assignments), which have no server-side backup

    Impact

    The force-close arrives without warning and terminates in-progress Claude Code sessions. Losing an agent mid-task is the practical damage, not the dialog itself.

    Note for other users hitting this: Reset is offered right next to Repair in the same Windows dialog, and it silently destroys local-only UI state (session groups). Conversation transcripts under ~/.claude/projects are unaffected.

    Workaround in use

    Running Claude Code via the standalone npm CLI (@anthropic-ai/claude-code, outside the MSIX package) is unaffected by the package state and survives the desktop app being force-closed.

    Not attempted

    LCU removal (the fix that worked in #70700) — the KBs on this machine differ from the reported one, and removing security updates was not an acceptable tradeoff here.

  7. github-actions commented on Sep 8, 2026

    @github-actions

    Closing for now — inactive for too long. Please open a new issue if this is still relevant.

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