[BUG] Claude Desktop (Windows MSIX) self-corrupts its own package on web fetch — Status becomes "Modified, NeedsRemediation", app refuses to launch

Preflight Checklist

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

What's Wrong?

Claude Desktop on Windows installs as an MSIX package into C:\Program Files\WindowsApps\, which Windows treats as immutable and hash-verifies on every launch.

After a clean install, Get-AppxPackage *claude* reports Status: Ok and the app runs normally. As soon as Claude uses a web fetch/browse tool to view an external URL, the app crashes and the package status flips to Modified, NeedsRemediation. On the next launch attempt, Windows refuses to start it and shows:

There's a problem with Claude. Reinstall the application from its original install location or contact your administrator.

The package version does not change between the working and broken state — no update occurs. This rules out update corruption. Something in the running app is writing into its own install directory, which invalidates the MSIX package signature and causes Windows to block execution.

Reproduced twice on the same machine on version 1.28929.0.0, both times triggered by a web fetch. Only a full uninstall + reinstall recovers it; Add-AppxPackage -Register against the manifest completes without error but does not clear the Modified status (the on-disk files are genuinely altered, not just metadata).

Additional relevant finding: the package reports SignatureKind: Developer rather than a production signature. This is likely related to why the MSIX runtime is strict about any modification, and is consistent with other reported install issues requiring Developer Mode to be enabled on Windows 11 25H2.

Secondary issue observed in the same session: failed launches leave orphaned claude processes that never acquire a window. These accumulate (I found 14, some a week old) and block subsequent launches, since Add-AppxPackage -Register fails with 0x80073D02 (resources in use) until they are force-killed.

What Should Happen?

Claude Desktop should write all runtime cache, temp, and fetched-content data to its designated writable location (%LOCALAPPDATA%\Packages\Claude_pzs8sxrjxfjjc\LocalCache\ or similar) rather than into its install directory under C:\Program Files\WindowsApps\.

Using a web fetch tool should not modify the installed package. Package status should remain Ok and the app should continue running normally.

Additionally, the app should be shipped with a production code-signing certificate rather than SignatureKind: Developer, and should cleanly terminate its own child processes on exit/relaunch rather than leaving orphans that block reinstallation.

Error Messages/Logs

Windows launch error dialog:
There's a problem with Claude. Reinstall the application from its original install location or contact your administrator.

--- Package state AFTER clean install (working) ---
PS> Get-AppxPackage *claude* | Select-Object Name, Version, Status
Name   Version     Status
----   -------     ------
Claude 1.28929.0.0     Ok

--- Package state AFTER web fetch crash (same version, no update) ---
PS> Get-AppxPackage *claude* | Select-Object Name, Version, Status
Name   Version                         Status
----   -------                         ------
Claude 1.28929.0.0 Modified, NeedsRemediation

--- Full package detail in broken state ---
Name                   : Claude
Publisher              : CN="Anthropic, PBC", O="Anthropic, PBC", L=San Francisco, S=California, C=US, SERIALNUMBER=4860621, OID.2.5.4.15=Private Organization, OID.1.3.6.1.4.1.311.60.2.1.2=Delaware, OID.1.3.6.1.4.1.311.60.2.1.3=US
PublisherId            : pzs8sxrjxfjjc
Architecture           : X64
Version                : 1.28929.0.0
PackageFamilyName      : Claude_pzs8sxrjxfjjc
PackageFullName        : Claude_1.28929.0.0_x64__pzs8sxrjxfjjc
InstallLocation        : C:\Program Files\WindowsApps\Claude_1.28929.0.0_x64__pzs8sxrjxfjjc
IsFramework            : False
IsResourcePackage      : False
IsBundle               : False
IsDevelopmentMode      : False
IsPartiallyStaged      : False
SignatureKind          : Developer
Status                 : Modified, NeedsRemediation

--- Re-register attempt (completes silently, does not fix) ---
PS> $manifest = (Get-AppxPackage *claude*).InstallLocation + "\AppxManifest.xml"
PS> Add-AppxPackage -DisableDevelopmentMode -Register $manifest
PS> Get-AppxPackage *claude* | Select-Object Name, Version, Status
Name   Version                         Status
----   -------                         ------
Claude 1.28929.0.0 Modified, NeedsRemediation

--- Re-register blocked by orphaned processes (before force-kill) ---
Add-AppxPackage : Deployment failed with HRESULT: 0x80073D02, The package could not be installed because resources it modifies are currently in use.
error 0x80073D02: Unable to install because the following apps need to be closed Claude_1.28929.0.0_x64__pzs8sxrjxfjjc.

--- Orphaned process accumulation (14 processes, oldest 7 days, none with a window) ---
PS> Get-Process *claude* | Select-Object Name, Id, StartTime, MainWindowTitle
Name      Id StartTime             MainWindowTitle
----      -- ---------             ---------------
claude  2312 7/15/2026 10:03:52 AM
claude 10796 7/13/2026 9:02:50 AM
claude 11856 7/15/2026 2:31:41 PM
claude 12952 7/13/2026 9:02:50 AM
claude 22792 7/13/2026 9:02:50 AM
claude 31536 7/13/2026 9:02:50 AM
claude 32420 7/13/2026 9:02:49 AM
claude 32460 7/13/2026 9:02:54 AM
claude 32956 7/16/2026 10:37:35 AM
claude 33244 7/13/2026 9:02:54 AM
claude 33448 7/16/2026 10:37:35 AM
claude 34388 7/13/2026 9:02:49 AM
claude 34768 7/20/2026 9:56:27 AM
claude 45460 7/20/2026 10:06:52 AM

--- Ruled out ---
Windows Defender: no detections against Claude/Anthropic/WindowsApps
  (Get-MpThreatDetection returned nothing matching)
Controlled Folder Access: disabled (EnableControlledFolderAccess = 0)
WebView2 Runtime: current, 151.0.4129.78
Windows Application event log: NO crash events logged for Claude/WebView in the
  2 hours surrounding the crashes — consistent with the AppX runtime blocking
  execution rather than an in-process exception
AppXDeployment/Operational log shows only:
  Event 325: "Claude_pzs8sxrjxfjjc is registered in good state, skip re-registering it"

Steps to Reproduce

1. On Windows, install Claude Desktop from https://claude.ai/download (right-click → Run as administrator).

1. Confirm the package is intact:

   Get-AppxPackage *claude* | Select-Object Name, Version, Status

Expected output: Status: Ok

1. Launch Claude Desktop and start any conversation.

1. Ask Claude to fetch or view any external URL. In my case:

"view https://coolors.co/palettes/trending"
Any request that invokes the web fetch/browse tool appears to trigger it.

1. The app crashes. On attempting to relaunch (Start menu or shortcut), Windows shows:

"There's a problem with Claude. Reinstall the application from its original install location or contact your administrator."

1. Re-check package status:

   Get-AppxPackage *claude* | Select-Object Name, Version, Status

Actual output: Status: Modified, NeedsRemediation — with the SAME version number as step 2. No update occurred between step 2 and step 6.

1. Attempt repair via manifest re-registration:

   Get-Process *claude* -ErrorAction SilentlyContinue | Stop-Process -Force
   Start-Sleep -Seconds 3
   $manifest = (Get-AppxPackage *claude*).InstallLocation + "\AppxManifest.xml"
   Add-AppxPackage -DisableDevelopmentMode -Register $manifest
   Get-AppxPackage *claude* | Select-Object Name, Version, Status

The command completes without error but Status remains Modified, NeedsRemediation.
(Note: if the orphaned processes from step 5 are not force-killed first, this
fails with HRESULT 0x80073D02 "resources currently in use".)

1. Only a full uninstall + wipe + reinstall recovers the app:

   Get-Process *claude* -ErrorAction SilentlyContinue | Stop-Process -Force
   Start-Sleep -Seconds 3
   Get-AppxPackage *claude* | Remove-AppxPackage
   Remove-Item -Recurse -Force "$env:APPDATA\Claude" -ErrorAction SilentlyContinue
   Remove-Item -Recurse -Force "$env:LOCALAPPDATA\AnthropicClaude" -ErrorAction SilentlyContinue
   Remove-Item -Recurse -Force "$env:LOCALAPPDATA\Packages\Claude_pzs8sxrjxfjjc" -ErrorAction SilentlyContinue

Then reinstall as administrator. Status returns to Ok.

1. Repeat step 4. The failure reproduces.

Observed 3 crashes and 2 full reinstalls in a single day, all on version 1.28929.0.0.

Claude Model

Opus

Is this a regression?

Yes, this worked in a previous version

Last Working Version

1.18286.0.0 was running without this specific self-corruption behavior earlier the same day, prior to the auto-update to 1.28929.0.0.

Claude Code Version

Not applicable — this is Claude Desktop, not the Claude Code CLI. Claude Desktop package version: 1.28929.0.0 (PackageFullName: Claude_1.28929.0.0_x64__pzs8sxrjxfjjc)

Platform

Anthropic API

Operating System

Windows

Terminal/Shell

PowerShell

Additional Information

Root cause hypothesis

The app appears to write cache or fetched content into its own install directory
under C:\Program Files\WindowsApps\Claude_<version>_x64__pzs8sxrjxfjjc\. MSIX
packages in that location are hash-verified by Windows on every launch and are
immutable by design. Any write invalidates the package and Windows blocks
execution with the "reinstall from its original install location" error.

The key evidence that this is self-inflicted rather than external corruption:
the package version is identical before and after the failure. No update ran.
The only intervening action was a web fetch.

Related open issues

This may share a root cause with several existing Windows packaging reports:

• #50285 — Claude Desktop failed to launch on Windows 11 25H2
• #25829 — installation fails, "couldn't install please check for software updates"
• #26457 / #25385 — "trusted app installs must be enabled" (Developer Mode requirement)
• #42776 — Claude Code Desktop fails to relaunch due to orphaned process file lock

(matches the process-accumulation behavior documented above)

The SignatureKind: Developer finding may be the common thread across all of these.

Impact

Three crashes and two full reinstalls in one working day, each requiring a
~10 minute uninstall/wipe/reinstall cycle plus re-authentication. Local chat
history/sidebar is cleared on each reinstall (recovers on sync, but is disruptive
mid-session). This makes the web fetch tool effectively unusable on Windows Desktop.

Current workaround

Avoid the web fetch/browse tool entirely in Claude Desktop on Windows. Fetch
pages manually in a browser and paste content in.