Pit record
A corrupted or cold npx cache makes an MCP server fail to start or time out
An npx-launched MCP server that intermittently fails or yields 'Client closed' / 'MCP error -32001: Request timed out' is often a npx/npm cache problem: an interrupted download leaves a partial package, or a cold first download exceeds the client startup timeout. Clear the cache or pre-install the package.
Markdown mirror | Canonical source
Fast answer
Problem: npx-launched MCP server worked before and now fails, or fails only on first launch
Root cause: npx downloads the package into the npm cache before running it.
Fix first: Clear the npm/npx cache and relaunch.
Verify: Relaunch after clearing the cache or pre-installing.
Queries this answers
- comment confirming a corrupted npx cache from network errors caused the server to crash; clearing it fixed startup
- comment confirming a corrupted npx cache from network errors caused the server to crash; clearing it fixed startup fix
- comment confirming a corrupted npx cache from network errors caused the server to crash; clearing it fixed startup root cause
- Client closed / -32001 Request timed out around npx MCP startup
- Client closed / -32001 Request timed out around npx MCP startup fix
- Client closed / -32001 Request timed out around npx MCP startup root cause
- A corrupted or cold npx cache makes an MCP server fail to start or time out
- A corrupted or cold npx cache makes an MCP server fail to start or time out fix
Record metadata
| Status | verified |
|---|---|
| Confidence | medium |
| Created | 2026-06-21 |
| Updated | 2026-06-21 |
| Last verified | 2026-06-21 |
| Affected tools | claude-desktop, cursor, cline, mcp-server |
| Tags | mcp, npx, cache, startup, timeout, error-32001 |
Common search queries
- mcp-npx-cache-corrupted-server-fails-to-start
- mcp npx cache corrupted server fails to start
- A corrupted or cold npx cache makes an MCP server fail to start or time out
- A corrupted or cold npx cache makes an MCP server fail to start or time out fix
- A corrupted or cold npx cache makes an MCP server fail to start or time out root cause
- cache
- startup
- timeout
- error-32001
- claude-desktop
- cursor
- cline
Symptoms
- npx-launched MCP server worked before and now fails, or fails only on first launch
- client log shows Client closed and/or MCP error -32001: Request timed out
- the failure is intermittent and sometimes clears up on its own
- a recent flaky network or interrupted install preceded it
Environment
| runtime | Node.js |
|---|---|
| package_manager | npm |
| constraints | MCP server launched via npx -y <package>, client enforces a startup timeout |
Root cause
- npx downloads the package into the npm cache before running it.
- An interrupted or rate-limited fetch can leave a partial or corrupted package, so the next launch crashes on missing files.
- A genuine cold download can exceed the client's startup timeout, producing -32001: Request timed out.
Fix
Clear the npm/npx cache and relaunch.
npm cache clean --forcePre-install the package so launch does not depend on a fresh download, and point the config at it.
npm i -g <package>If it was a cold-start timeout, retry once the package is cached, or raise the client's MCP startup timeout if configurable.
Verification
Relaunch after clearing the cache or pre-installing.
Expected: Server starts on first try with no Client closed / -32001: Request timed out.
Workarounds
- Pin a globally installed package by absolute path instead of relying on npx download at launch.
Anti-patterns
- Repeatedly editing the config when the real fault is a half-written cache.
- Assuming the server package is broken when a clean cache fixes it.
Sources
No matching fix?
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