[BUG] WebFetch to arthive.com crashes and corrupts Claude Desktop install (Windows)

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?

Summary

When Claude (running in Claude Desktop) attempts to WebFetch a page on arthive.com, the app crashes. This has happened 3+ times. Unlike an ordinary WebFetch hang/timeout, the crash leaves the local app state corrupted — the app cannot simply be relaunched and requires a full uninstall/reinstall to recover, which wipes local app data (chat history, settings) because the underlying Windows package removal is non-data-preserving (see install log details below).

Environment

• OS: Windows 10 (build 10.0.19045), Windows edition: Core
• App: Claude Desktop, MSIX package Claude_pzs8sxrjxfjjc
• Installer build: 03c61d06f8e01a4db2273b9514e225f21d2ba62e
• Affected versions seen in logs: 1.24012.1.0, 1.24012.9.0

Steps to Reproduce

1. In Claude Desktop, ask Claude to fetch/access a page on arthive.com (via WebFetch tool).
2. App hangs, then crashes.
3. Relaunching the app fails / app is left in a broken state.
4. Only fix found: full uninstall and reinstall via Claude Setup.exe, which loses all local app data.
5. Repeat — this has now happened 3 times with the same site.

Impact

• Repeated, reproducible crash tied to a specific site (arthive.com) — suggests WebFetch is not handling this site's response gracefully (no timeout / no graceful degradation), consistent with other reported WebFetch hang issues (e.g. #11650, #8980).
• Unlike those reports, the crash here corrupts the local install, not just the current session — a materially more severe failure mode.
• Recovery requires full reinstall, which on Windows is itself broken by a related bug: AddPackage fails with HRESULT 0x80073CF6 because CoworkVMService cannot be cleanly stopped (Access is denied), forcing a non-data-preserving package removal. This matches issue #49655. Full log excerpt below.

Relevant log excerpt (ClaudeSetup.log)

Removing conflicting CoworkVMService...
WARNING: failed to remove conflicting service: could not open CoworkVMService: Access is denied.
Checking for existing Claude MSIX packages...
Removing: Claude_1.24012.9.0_x64__pzs8sxrjxfjjc
Windows rejected data-preserving removal for Claude_1.24012.9.0_x64__pzs8sxrjxfjjc (0x80073CFA, requires developer mode); relying on in-place update
Installing via AddPackage (current-user)...
WARNING: AddPackage failed over an existing install (AddPackage failed with HRESULT 0x80073CF6); removing wedged package(s) and retrying — app data will not be preserved
Removing wedged package: Claude_1.24012.9.0_x64__pzs8sxrjxfjjc
WARNING: Windows rejected PreserveApplicationData for Claude_1.24012.9.0_x64__pzs8sxrjxfjjc (0x80073CFA, requires developer mode); retrying removal without it — app data will not be preserved
MSIX installation failed: AddPackage failed even after removing wedged packages: AddPackage failed with HRESULT 0x80073CF6

Note: this specific install failure resolved after a full system reboot (which cleared the stuck CoworkVMService — confirmed via sc.exe query CoworkVMService returning error 1060, "service not installed") plus enabling Windows Developer Mode. But data was still lost on that reinstall.

Expected Behavior

1. WebFetch should time out gracefully on slow/unresponsive/bot-blocking sites instead of crashing the app.
2. A WebFetch-related crash should never corrupt the local app installation to the point a reinstall is required.
3. Separately: Windows reinstall/update should not require developer mode or destroy local app data just to recover from a stuck CoworkVMService — the installer should stop the service cleanly (with elevated force-shutdown flags) before attempting package removal, per the recommendation already raised in #49917/#56949/#49655.

Requested Action

• Investigate why arthive.com specifically triggers this (headers, response size, redirect behavior, bot-blocking, etc.) and add a timeout/graceful-degradation path to WebFetch.
• Investigate why the crash corrupts local state rather than just failing the single tool call.
• Link/dedupe against #49655 for the CoworkVMService install issue, which is a contributing factor to why recovery is so costly (full data loss).

Attachments

• ClaudeSetup.log (full installer log covering multiple crash/reinstall cycles, showing the CoworkVMService and AddPackage failures)

What Should Happen?

WebFetch should time out gracefully on slow/unresponsive/bot-blocking sites instead of crashing the app. A WebFetch-related crash should never corrupt the local app installation to the point a reinstall is required.

Error Messages/Logs

Removing conflicting CoworkVMService...
WARNING: failed to remove conflicting service: could not open CoworkVMService: Access is denied.
Checking for existing Claude MSIX packages...
Removing: Claude_1.24012.9.0_x64__pzs8sxrjxfjjc
Windows rejected data-preserving removal for Claude_1.24012.9.0_x64__pzs8sxrjxfjjc (0x80073CFA, requires developer mode); relying on in-place update
Installing via AddPackage (current-user)...
WARNING: AddPackage failed over an existing install (AddPackage failed with HRESULT 0x80073CF6); removing wedged package(s) and retrying — app data will not be preserved
Removing wedged package: Claude_1.24012.9.0_x64__pzs8sxrjxfjjc
WARNING: Windows rejected PreserveApplicationData for Claude_1.24012.9.0_x64__pzs8sxrjxfjjc (0x80073CFA, requires developer mode); retrying removal without it — app data will not be preserved
MSIX installation failed: AddPackage failed even after removing wedged packages: AddPackage failed with HRESULT 0x80073CF6

Steps to Reproduce

1. In Claude Desktop, ask Claude to fetch/access a page on arthive.com (via WebFetch tool).
2. App hangs, then crashes.
3. Relaunching the app fails / app is left in a broken state.
4. Only fix found: full uninstall and reinstall via Claude Setup.exe, which loses all local app data.
5. This has now happened 3 times with the same site.

Claude Model

None

Is this a regression?

I don't know

Last Working Version

_No response_

Claude Code Version

Claude Desktop 1.24012.9 (MSIX)

Platform

Anthropic API

Operating System

Windows

Terminal/Shell

Other

Additional Information

ClaudeSetup.log
Possibly related to #49655 (CoworkVMService blocking clean package removal on Windows) — same service/lock pattern appears in the attached log.