[BUG] Claude Desktop Installation Fails on Windows 11 - Signature Verification & Unable to Load

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 Installation Fails on Windows 11 - Signature Verification & Unable to Load

Summary

Claude Desktop installer fails during signature verification with a PowerShell PATH error, and subsequent launch attempts result in "unable to load" errors.

Environment

• OS: Windows 11
• System: Personal laptop (administrator account)
• Developer Mode: Enabled
• App Sideloading: Enabled

Issue Description

After enabling Developer Mode and App Sideloading in Windows 11 settings, attempting to install Claude Desktop results in a signature verification failure that claims PowerShell cannot be found, despite PowerShell being functional and used daily.

Error 1: Installation Failure

Installation failed: signature verification failed: signature check failed: exec: "powershell.exe": executable file not found in %PATH%
stderr:

Details:

• Error occurs during installer signature verification step
• PowerShell is installed and functional at C:\Windows\System32\WindowsPowerShell\v1.0\powershell.exe
• PowerShell is accessible from Command Prompt and PowerShell itself
• Error persists across multiple download attempts and fresh downloads from https://claude.com/download

Error 2: Application Won't Load

After the installer completes (despite the signature verification error), attempting to launch Claude Desktop results in:

/feedback unable to load claude desktop

• Application icon appears in Start menu
• Clicking to launch shows no error dialog
• Application fails to initialize or display window
• No error messages in Event Viewer

Steps to Reproduce

1. Enable Developer Mode in Settings → Privacy & Security → For developers
2. Enable App Sideloading in Settings → Apps → Advanced app settings
3. Download Claude Desktop installer from https://claude.com/download (Windows standard version)
4. Run installer
5. Observe signature verification failure with PowerShell PATH error
6. Installer completes despite error
7. Attempt to launch Claude Desktop from Start menu
8. Observe "unable to load" behavior

Expected Behavior

• Installer should successfully verify signatures and complete without PowerShell PATH errors
• Claude Desktop should launch and display the chat interface
• Application should be fully functional

Actual Behavior

• Installer fails during signature verification claiming PowerShell is not in PATH (false negative)
• Installer completes despite failure
• Claude Desktop will not launch or load

Additional Context

• Claude Code CLI (v2.1.39) installed and working correctly via npm
• Claude.ai web interface works normally
• No IT policies or managed device settings present (personal device)
• System is fully updated to latest Windows 11 build
• UAC is enabled (standard Windows security setting)
• Fresh installation - no previous Claude Desktop versions present
• This appears to be part of a broader Windows installation issue pattern emerging around the Cowork release (Feb 10, 2026)

Related Issues

This issue is related to several other Windows installation failures reported in the same timeframe:

• [#25162](https://github.com/anthropics/claude-code/issues/25162) - Existing Squirrel-based Claude Desktop users cannot upgrade to MSIX — reports sideloading errors and installation failures
• [#25149](https://github.com/anthropics/claude-code/issues/25149) - Claude Desktop installer falsely detects Windows S Mode
• [#25075](https://github.com/anthropics/claude-code/issues/25075) - Claude Desktop installer hijacks Claude Code CLI command
• [#24918](https://github.com/anthropics/claude-code/issues/24918) - Cowork Windows cannot connect to Claude API on Windows 11 Home

These related issues suggest a systematic problem with the Windows deployment/installer introduced with the Cowork release.

Possible Root Causes

1. Installer's PowerShell detection logic is faulty—it's not correctly identifying PowerShell in PATH even though it exists at standard location
2. Installer signature verification process has a bug that prevents proper PowerShell invocation
3. The installer that completes despite the error leaves the application in a broken state

Workaround

Currently using Claude Code CLI and web interface. Desktop GUI application is not functional.

What Should Happen?

The installation should execute with no errors.

Error Messages/Logs

Steps to Reproduce

Steps to Reproduce

1. Enable Developer Mode in Settings → Privacy & Security → For developers
2. Enable App Sideloading in Settings → Apps → Advanced app settings
3. Download Claude Desktop installer from https://claude.com/download (Windows standard version)
4. Run installer
5. Observe signature verification failure with PowerShell PATH error
6. Installer completes despite error
7. Attempt to launch Claude Desktop from Start menu
8. Observe "unable to load" behavior

Claude Model

Other

Is this a regression?

I don't know

Last Working Version

_No response_

Claude Code Version

https://claude.com/download latest windows version

Platform

Anthropic API

Operating System

Windows

Terminal/Shell

PowerShell

Additional Information

_No response_