[Bug] pdf-viewer MCP built-in server - UtilityProcess spawn timeout (Claude Desktop, Windows 10)

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?

The built-in pdf-viewer MCP server fails to initialize with "UtilityProcess spawn timeout" on every attempt. The server starts but never completes the spawn process within the timeout window.

What Should Happen?

The pdf-viewer MCP server should initialize and connect successfully, as it did before May 20, 2026.

Error Messages/Logs

2026-05-26T22:10:03Z [pdf-viewer] Initializing server...
2026-05-26T22:10:03Z [pdf-viewer] Using built-in Node.js for MCP server: pdf-viewer
2026-05-26T22:10:08Z [pdf-viewer] [error] UtilityProcess spawn timeout

Steps to Reproduce

1. Open Claude Desktop on Windows 10
2. Go to Settings → Developer → Local MCP Servers
3. Observe pdf-viewer MCP server status — it shows "failed"
4. Check logs: the error "UtilityProcess spawn timeout" appears consistently

Claude Model

None

Is this a regression?

Yes, this worked in a previous version

Last Working Version

Claude Desktop 1.8089

Claude Code Version

N/A — this is a Claude Desktop issue

Platform

Other

Operating System

Windows

Terminal/Shell

Other

Additional Information

• Issue persists across multiple Claude Desktop versions: 1.8089, 1.8555, 1.9255
• The external filesystem MCP server continues to work normally
• First failure logged: 2026-05-20T22:41:43Z
• Still failing as of: 2026-05-26T22:10:08Z
• This appears to be a regression introduced by a Claude Desktop update around May 20, 2026