MCP inspector UI hangs / times out if the MCP server throws an error #655

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1. dhawalkp

   added

   bugSomething isn't workingSomething isn't working

   on Jul 28, 2025
2. LucaButBoring commented on Jul 29, 2025

   

   LucaButBoring

   on Jul 29, 2025

   Contributor

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   To add a specific error case during a tool call:

   Error from MCP server: Error: Error POSTing to endpoint (HTTP 400): {"jsonrpc":"2.0","id":0,"error":{"code":-32600,"message":"Invalid request - Malformed JSON-RPC request"}}
3. olaservo

   added

   p2-medium

   on Aug 21, 2025
4. olaservo commented on Aug 28, 2025

   

   olaservo

   on Aug 28, 2025

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   @claude could you help investigate this issue?
5. claude

   added a commit that references this issue on Aug 28, 2025

   fix: Forward MCP server error responses instead of converting to time…

   ...

   This issue will close once commit d3504dc is merged into the 'main' branch.

   d3504dc
6. modelcontextprotocol

   deleted a comment from claude on Aug 28, 2025
7. cliffhall

   added

   v1

   closed-v1-deprecatedClosed: v1 is deprecated and accepting security fixes onlyClosed: v1 is deprecated and accepting security fixes only

   on Aug 1, 2026
8. cliffhall commented on Aug 1, 2026

   

   cliffhall

   on Aug 1, 2026

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   Closing: v1 is deprecated.

   Thank you for reporting this, and apologies for the long wait for a response.

   v1 will receive security fixes only — this issue describes a functionality, compatibility, or usability problem rather than a vulnerability, so it is being closed against v1. This is not a judgment on whether the problem is real — it's a consequence of the v1 line being frozen. This is happening as part of #1872.

   If this still happens in v2, we'd genuinely like to know. v2 is a complete rewrite — three clients over a shared core — so many v1 behaviours no longer exist in the same form. Please open a fresh issue against v2 with steps to reproduce, and we'll look at it. Note that we accept external contributions as issues rather than pull requests; maintainers handle design and implementation through a prompt-driven workflow. See CONTRIBUTING.md.

   Thanks for taking the time to report it.
9. cliffhall

   closed this as not plannedon Aug 1, 2026