ABP Studio MCP bridge returns invalid messages to MCP clients (Claude Code and MCP Inspector) #10720

4 Answer(s)

• 

  0

  AI-Bot created 3 months ago

  Support Team ABP Agent

  • This is a known issue in ABP Studio MCP server CLI output/handshake that was fixed in ABP Studio 2.1.9 (“Fixed MCP server CLI output problem.”). Your symptoms (Claude Code timeout; MCP Inspector Zod validation errors like expected string/number, received null and unrecognized error field) match what happens when the MCP client receives non-conformant messages during the MCP handshake.
  • Solution (recommended)
    1. Update ABP Studio to at least 2.1.9 (or any newer version).
    2. Update the ABP Studio CLI tool too:

  dotnet tool update -g Volo.Abp.Studio.Cli
  

  3. Restart ABP Studio (ensure a solution is loaded), then rerun:

  abp mcp-studio
  

  4. Reconnect from Claude Code / MCP Inspector; it should complete handshake and list tools.

  • If you cannot update immediately (workaround)

    • There isn’t a reliable client-side workaround if the server emits invalid MCP messages; MCP clients will correctly reject them. Updating is the practical fix.

  • If after updating you still see issues, treat it as a Studio product issue and contact support with Studio logs (since this is ABP Studio/Commercial tooling behavior): https://abp.io/contact

  Less obvious references:

  • https://abp.io/docs/10.4//studio/release-notes
  • https://abp.io/docs/latest/studio/release-notes

  ---

  This response was generated by AI. If it didn’t solve your problem, feel free to post a new answer — our support team will jump in to help you soon.

  Markdown supported.

  Copy, paste, or drag & drop images and files (max 100 MB per file, 100 MB total per post)

  Save Cancel
• 

  0

  AlessandroLittera created 3 months ago

  Thank you.

  I have already performed these steps.

  Environment:

  ABP Studio Team Edition 10.4.1 Volo.Abp.Studio.Cli 3.0.4 Claude Code 2.1.169 MCP Inspector 0.22.0 Windows 11

  I have already:

  • Updated Volo.Abp.Studio.Cli to 3.0.4.

  • Restarted ABP Studio.

  • Loaded the solution.

  • Verified that the AI Agent works correctly.

  • Tested both:

    abp mcp-studio

    and

    abp mcp-studio --endpoint http://localhost:38271/mcp/

  • Reproduced the same problem with MCP Inspector, not only with Claude Code.

  The bridge process stays alive, but the MCP handshake never completes.

  MCP Inspector reports:

  ZodError Invalid input: expected string/number, received null Unrecognized key: "error"

  Therefore this does not appear to be a client-side issue.

  Could you please escalate this to the ABP Studio team?

  I can provide the complete MCP Inspector logs if necessary.

  Markdown supported.

  Copy, paste, or drag & drop images and files (max 100 MB per file, 100 MB total per post)

  Save Cancel
• 

  0

  yekalkan created 3 months ago

  Support Team Fullstack Developer

  Hi @AlessandroLittera

  We've removed the ABP Studio MCP server support after the launch of ABP Agent.

  We also removed the document but somehow it is still present. We'll check it. https://github.com/abpframework/abp/pull/25518/

  Markdown supported.

  Copy, paste, or drag & drop images and files (max 100 MB per file, 100 MB total per post)

  Save Cancel
• 

  -1

  yekalkan created 3 months ago

  Support Team Fullstack Developer

  Hi again,

  We decided to bring the ABP Studio MCP Server back in future releases, fyi.

  Markdown supported.

  Copy, paste, or drag & drop images and files (max 100 MB per file, 100 MB total per post)

  Save Cancel