[BUG] Claude Desktop Windows installer fails with AddPackage HRESULT 0x80073CF6 after an earlier "successful" install left the package in an inconsistent state

[ARHAEEM]

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?

Environment

• OS: Windows 11 Professional, build 10.0.22631
• Architecture: x64
• Installer: Claude Setup (1).exe (downloads https://api.anthropic.com/api/desktop/win32/x64/msix/latest/redirect)
• MSIX: 223,023,064 bytes, SHA256 4c664c5390a4d5b46286158f67e21102431a1c9863dc5edb2b8683ef69e1e300
• Package family: Claude_pzs8sxrjxfjjc
• Previously installed version: Claude_1.3109.0.0_x64__pzs8sxrjxfjjc

What's wrong

On an existing install, trying to update or reinstall Claude Desktop fails repeatedly. The user-facing dialogs show:

1. Installation failed: AddPackage failed: AddPackage failed with HRESULT 0x80073CF6
2. App installation failed with error message: An internal error occurred with error 0x80073D05.
3. Administrator access is required to install Claude with full features. You can try again or install without Cowork. (misleading — the process is already elevated)

What Should Happen?

Suggested fixes on the installer side

1. Do not claim success when RemovePackage fails. When the existing package can't be removed, the installer should either retry with force flags (e.g., DeploymentOptions.ForceApplicationShutdown | ForceTargetApplicationShutdown | RemoveForAllUsers) or abort with a clear error and a remediation link. Silently calling AddPackage on a non-removed package produces the wedged state reproduced here.
2. Surface CoworkVMService access-denied failures properly. "Administrator access is required" is misleading when Is elevated: true is already in the log — the real cause is the service-handle ACL or another process holding it. Please report the underlying OpenSCManager/OpenService error code in the dialog.
3. Offer a recovery flow. Once the package is wedged, neither Remove-AppxPackage, Remove-AppxPackage -AllUsers, nor the installer can clear it (same finding in [BUG] Claude Desktop Windows installation permanently broken – MSIX stuck in Staged state #47877). A "repair" / "force clean" option in the installer would unblock affected users.
4. Investigate the 0x80073D05 in the user-facing dialog. It doesn't appear literally in the log (log shows 0x80073CF6) — the mapping between the dialog code and the log code should be consistent.

What worked around it

Nothing so far — all Remove-AppxPackage attempts, registry cleanup, and fresh installer runs fail identically.

Error Messages/Logs

## Full log

Uploaded as `ClaudeSetup.log` (attach the file in the GitHub UI — sanitized: only paths contain the Windows username `admin`).

Steps to Reproduce

Reproduction

1. Windows 11 Pro with an existing Claude_1.3109.0.0_x64__pzs8sxrjxfjjc install and a CoworkVMService present
2. Run Claude Setup (1).exe to update/reinstall
3. First run appears to succeed but leaves the package wedged
4. Every subsequent run fails with AddPackage HRESULT 0x80073CF6

Log analysis (key excerpts)

Run 1 — "successfully installed" but likely left the package broken

2026/04/17 15:29:26.772280 Removing conflicting CoworkVMService...
2026/04/17 15:29:26.772280 WARNING: failed to remove conflicting service: could not open CoworkVMService: Access is denied.
2026/04/17 15:29:26.784544 Removing: Claude_1.3109.0.0_x64__pzs8sxrjxfjjc
2026/04/17 15:29:26.790294 WARNING: Remove failed for Claude_1.3109.0.0_x64__pzs8sxrjxfjjc: RemovePackage failed with HRESULT 0x80073CFA
2026/04/17 15:29:26.798289 Removing (user): Claude_1.3109.0.0_x64__pzs8sxrjxfjjc
2026/04/17 15:29:26.803317 WARNING: Remove failed for Claude_1.3109.0.0_x64__pzs8sxrjxfjjc: RemovePackage failed with HRESULT 0x80073CFA
2026/04/17 15:29:26.803317 Installing MSIX: ...
2026/04/17 15:29:26.804561 Standard install (not split-account), using AddPackage
2026/04/17 15:29:27.555410 MSIX package installed successfully
2026/04/17 15:29:27.614310 === Claude Setup completed successfully ===

Two issues here:

• CoworkVMService removal fails with Access is denied even though Is elevated: true. The service is being opened with a handle level the elevated process doesn't have, or something else (antivirus, group policy, another user's session) holds it.
• Both RemovePackage calls for the existing package fail with 0x80073CFA (ERROR_REMOVE_FAILED), yet the installer proceeds to AddPackage on top of the non-removed package and claims success. This is almost certainly where the wedge is created.

Runs 2, 3, 4 — consistent 0x80073CF6 failure

2026/04/17 15:30:37.814390 Checking for existing Claude MSIX packages...
2026/04/17 15:30:37.837840 Installing MSIX: ...
2026/04/17 15:30:37.839576 Extracted family name from MSIX manifest: Claude_pzs8sxrjxfjjc
2026/04/17 15:30:37.839576 Standard install (not split-account), using AddPackage
2026/04/17 15:30:37.839576 Installing via AddPackage (current-user)...
2026/04/17 15:30:52.848301 MSIX installation failed: AddPackage failed: AddPackage failed with HRESULT 0x80073CF6

Note that the package-enumeration step finds nothing to remove (no Removing: lines), yet AddPackage is rejected 13–17 seconds in with ERROR_PACKAGE_REGISTRATION_FAILED. That's the classic signature of an MSIX stuck in a partially-registered state — not enumerable by the deployment API, but the package family name is still claimed somewhere in the Appx store / WindowsApps filesystem.

Claude Model

None

Is this a regression?

Yes, this worked in a previous version

Last Working Version

No response

Claude Code Version

1.3109.0.0_x64

Platform

Anthropic API

Operating System

Windows

Terminal/Shell

Other

Additional Information

ClaudeSetup.log

[github-actions]

Found 3 possible duplicate issues:

1. [BUG] Claude Desktop MSIX Installation Fails with HRESULT 0x80073CF6 on Windows 11 #48437
2. [BUG] Claude Desktop update fails with 0x80073CF6 when CoworkVMService is running (Windows) #49655
3. [BUG] Claude Desktop Windows installation permanently broken – MSIX stuck in Staged state #47877

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

[ARHAEEM]

Workaround: Claude Desktop install fails on Windows 11 with 0x80073CF6 (and 0x80073D05)

‌

TL;DR — If the Anthropic Squirrel/MSIX installer keeps failing with AddPackage failed with HRESULT 0x80073CF6, the cause is almost always a half-removed previous install that left:

1. A stale CoworkVMService service (non-removable by the installer without admin)
2. A staged/registered MSIX package (Claude_pzs8sxrjxfjjc) stuck in an inconsistent state
3. Locked per-package registry hives (User.dat / UserClasses.dat under SystemAppData\Helium) that block Windows from cleaning up old AppData.

The installer doesn't elevate enough to fix any of this. The following procedure cleans up everything deterministically and re-registers the app.

⚠️ A reboot in the middle is mandatory — do not skip it. The locked hives only release on sign-out/reboot after the package is unregistered.

This worked on Windows 11 Pro (build 10.0.22631.6199) after 4 failed installer attempts producing 0x80073CF6. Same steps should resolve the related 0x80073D05 (ERROR_DELETING_EXISTING_APPLICATION_DATA_STORE_FAILED) and 0x80073D28 (Administrator privileges required to install packaged service) that you'll hit if you only do half the cleanup.

---

Why the installer keeps failing

Looking at %TEMP%\ClaudeSetup.log, the failure chain is:

WARNING: CoworkVMService already exists (potential conflict)
WARNING: failed to remove conflicting service: could not open CoworkVMService: Access is denied.
Removing: Claude_1.3109.0.0_x64__pzs8sxrjxfjjc
WARNING: Remove failed ... RemovePackage failed with HRESULT 0x80073CFA
Installing via AddPackage (current-user)...
MSIX installation failed: AddPackage failed: AddPackage failed with HRESULT 0x80073CF6

Then, if you pre-stage with DISM and retry, the deeper root cause surfaces in Get-AppPackageLog:

503  The file system entries for package Claude_pzs8sxrjxfjjc could not be cleaned up after reboot.
5224 Error while deleting file ...\Claude_pzs8sxrjxfjjc\SystemAppData\Helium\User.dat. Error Code : 0x20.
5224 Error while deleting file ...\SystemAppData\Helium\UserClasses.dat. Error Code : 0x20.

0x20 = ERROR_SHARING_VIOLATION. Windows has the per-package registry hives mounted for your session. Killing claude.exe does not release them — only unregistering the package, then rebooting (so nothing re-mounts them), then deleting the folder works.

---

Full fix (step by step)

Phase 1 — Clean up (run in PowerShell as Administrator)

# 1. Kill anything from the previous install
Get-Process *claude*,*chrome-native-host*,*cowork* -ErrorAction SilentlyContinue | Stop-Process -Force

# 2. Remove the registered package (per-user and all-users)
Get-AppxPackage -Name "Claude*" | Remove-AppxPackage -ErrorAction SilentlyContinue
Get-AppxPackage -AllUsers -Name "Claude*" | Remove-AppxPackage -AllUsers -ErrorAction SilentlyContinue

# 3. Remove any provisioned (system-staged) copy so Windows doesn't auto-re-register on next login
Get-AppxProvisionedPackage -Online |
    Where-Object { $_.DisplayName -like "Claude*" -or $_.PackageName -like "*Claude*" } |
    Remove-AppxProvisionedPackage -Online

# 4. Delete the conflicting service (the installer can't do this non-elevated)
sc.exe stop CoworkVMService
sc.exe delete CoworkVMService
Remove-Item "HKLM:\SYSTEM\CurrentControlSet\Services\CoworkVMService" -Recurse -Force -ErrorAction SilentlyContinue

# 5. Clean leftover Squirrel / Claude folders
Remove-Item "$env:LOCALAPPDATA\AnthropicClaude"   -Recurse -Force -ErrorAction SilentlyContinue
Remove-Item "$env:LOCALAPPDATA\SquirrelTemp"      -Recurse -Force -ErrorAction SilentlyContinue
Remove-Item "$env:LOCALAPPDATA\SquirrelClowdTemp" -Recurse -Force -ErrorAction SilentlyContinue
Remove-Item "$env:APPDATA\Claude"                 -Recurse -Force -ErrorAction SilentlyContinue
Remove-Item "$env:TEMP\Claude-*.msix"             -Force          -ErrorAction SilentlyContinue

Phase 2 — 🔴 REBOOT (mandatory — do NOT skip)

Reboot Windows. This is the step that releases the locked User.dat / UserClasses.dat hives from your user session. Skipping this guarantees you'll get 0x80073D05 on the next install attempt.

After rebooting, do not launch Claude, Cowork, or any Anthropic app. Go straight to PowerShell.

Phase 3 — Delete the leftover AppData (PowerShell as Administrator)

# Hives are now unloaded — these should succeed silently
Remove-Item "$env:LOCALAPPDATA\Packages\Claude_pzs8sxrjxfjjc"  -Recurse -Force
Remove-Item "C:\ProgramData\Packages\Claude_pzs8sxrjxfjjc"     -Recurse -Force -ErrorAction SilentlyContinue

# Sanity check — should return nothing
reg query "HKU" | Select-String "Claude"

If a hive is still mounted (the reg query returned a hit), unload it:

reg unload "HKU\<the-exact-key-name-from-the-query>"

Then re-run the two Remove-Item commands.

Phase 4 — Download and stage the MSIX (PowerShell as Administrator)

$TempPath = "C:\ClaudeTemp"
New-Item -Path $TempPath -ItemType Directory -Force | Out-Null

Invoke-WebRequest `
    -Uri "https://claude.ai/api/desktop/win32/x64/msix/latest/redirect" `
    -OutFile "$TempPath\Claude.msix" -UseBasicParsing
Unblock-File -Path "$TempPath\Claude.msix"

# Stage into the system image (optional but avoids AppX Deployment Service races)
dism.exe /Online /Add-ProvisionedAppxPackage /PackagePath:"$TempPath\Claude.msix" /SkipLicense

Phase 5 — Install (PowerShell as Administrator — critical)

The MSIX contains a packaged service (CoworkVMService). Registering a packaged service requires admin — a non-elevated Add-AppxPackage will fail with 0x80073D28.

Add-AppxPackage -Path "C:\ClaudeTemp\Claude.msix" -ForceApplicationShutdown -ForceUpdateFromAnyVersion

No output = success.

Phase 6 — Verify and launch

Get-AppxPackage -Name "Claude*" | Select-Object Name, Version, PackageFullName
# Expect: Claude 1.3109.0.0 Claude_1.3109.0.0_x64__pzs8sxrjxfjjc

explorer.exe "shell:AppsFolder\Claude_pzs8sxrjxfjjc!Claude"

# Cleanup
Remove-Item "C:\ClaudeTemp" -Recurse -Force

---

Error-code quick reference

HRESULT	Meaning	What it tells you
0x80073CFA	ERROR_INSTALL_PREREQUISITE_FAILED on Remove	The installer can't remove the old package (usually because CoworkVMService still has a handle on files).
0x80073CF6	ERROR_PACKAGE_NOT_REGISTERED / merge failure	The register half of the "remove-then-add" failed. Inner code is in the event log.
0x80073D05	ERROR_DELETING_EXISTING_APPLICATION_DATA_STORE_FAILED	The AppData hive is locked. Unregister + reboot + delete %LOCALAPPDATA%\Packages\Claude_pzs8sxrjxfjjc.
0x80073D28	ERROR_DEPLOYMENT_BLOCKED_BY_POLICY (packaged service)	You're running Add-AppxPackage non-elevated. Re-run from an Administrator PowerShell.
0x20	ERROR_SHARING_VIOLATION (inside Get-AppPackageLog)	The exact file that's locked — grep the log for Error while deleting file to find which hive.

---

Why the Anthropic installer alone can't fix this

• The bootstrapper self-elevates to Full but still uses AddPackage per-user, which can't purge the stuck AppData hives from other sessions.
• The CoworkVMService removal requires SCM admin access even when the bootstrapper is "elevated" through UAC, because of how it was registered by the prior install.
• The installer does not unregister the package before trying to reinstall; it tries remove-then-add in one pass, and when remove fails it still proceeds to add — which is what triggers 0x80073CF6.

Running the phases above separately — with the reboot in the middle — sidesteps all three issues.