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[GH-ISSUE #265] issue: Waiting for application startup #120

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opened 2026-10-18 21:11:56 +00:00 by bsakaguchi · 3 comments
bsakaguchi commented 2026-10-18 21:11:56 +00:00
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Originally created by @gkjpettet on GitHub (Oct 18, 2025).
Original GitHub issue: https://github.com/open-webui/mcpo/issues/265

Check Existing Issues

  • I have searched the existing issues and discussions.
  • I am using the latest version of mcpo.

mcpo Version

v1.0

Open WebUI Version (if applicable)

v0.6.34

Operating System

macOS Tahoe

Browser (if applicable)

Safari 26.0.1

Confirmation

  • I have read and followed all instructions in README.md.
  • I am using the latest version of both MCPO and Open WebUI.
  • I have included the browser console logs.
  • I have included the Docker container logs.
  • I have listed steps to reproduce the bug in detail.

Expected Behavior

I have a custom MCP Server written in Xojo (https://github.com/gkjpettet/mcpwikipedia) that functions through stdout. It works perfectly with LM Studio and Claude Desktop. I am expecting it to be proxied by mcpo to an OpenAPI server.

Actual Behavior

mcpo hangs waiting for application startup.

Steps to Reproduce

  1. I launch my tool (mcpwikipedia) like this:
uvx mcpo --port 51332 -- /Users/garry/mcpservers/mcpwikipedia/mcpwikipedia --useragent="XojoMCPWikipediaSearch" --verbose=true
  1. This is the output in the Terminal:
Starting MCP OpenAPI Proxy on 0.0.0.0:51332 with command: stdbuf -o0 /Users/garry/mcpservers/mcpwikipedia/mcpwikipedia --useragent=XojoMCPWikipediaSearch
2025-10-18 13:39:46,162 - INFO - Starting MCPO Server...
2025-10-18 13:39:46,162 - INFO -   Name: MCP OpenAPI Proxy
2025-10-18 13:39:46,162 - INFO -   Version: 1.0
2025-10-18 13:39:46,162 - INFO -   Description: Automatically generated API from MCP Tool Schemas
2025-10-18 13:39:46,162 - INFO -   Hostname: Garrys-Mac-Studio.local
2025-10-18 13:39:46,162 - INFO -   Port: 51332
2025-10-18 13:39:46,162 - INFO -   API Key: Not Provided
2025-10-18 13:39:46,162 - INFO -   CORS Allowed Origins: ['*']
2025-10-18 13:39:46,162 - INFO -   Path Prefix: /
2025-10-18 13:39:46,162 - INFO -   Root Path: 
2025-10-18 13:39:46,162 - INFO - Configuring for a single Stdio MCP Server with command: stdbuf -o0 /Users/garry/mcpservers/mcpwikipedia/mcpwikipedia --useragent=XojoMCPWikipediaSearch
2025-10-18 13:39:46,162 - INFO - Uvicorn server starting...
INFO:     Started server process [929]
INFO:     Waiting for application startup.

  1. The mcpo server never spins up and I am not able to access the tool via Open API.

  2. Turning on verbose mode in my tool shows this:

2025-10-18 13:40:45,503 - INFO - Uvicorn server starting...
INFO:     Started server process [1007]
INFO:     Waiting for application startup.
Oct 18 13:40:45  mcpwikipedia[1014] <Warning>: mcpwikipedia starting...
Oct 18 13:40:45  mcpwikipedia[1014] <Warning>: mcpwikipedia received: {"method":"initialize","params":{"protocolVersion":"2025-06-18","capabilities":{},"clientInfo":{"name":"mcp","version":"0.1.0"}},"jsonrpc":"2.0","id":0}
Oct 18 13:40:45  mcpwikipedia[1014] <Warning>: Processing method: initialize
Oct 18 13:40:45  mcpwikipedia[1014] <Warning>: About to handle initialisation
Oct 18 13:40:45  mcpwikipedia[1014] <Warning>: {"method":"initialize","params":{"protocolVersion":"2025-06-18","capabilities":{},"clientInfo":{"name":"mcp","version":"0.1.0"}},"jsonrpc":"2.0","id":0}
Oct 18 13:40:45  mcpwikipedia[1014] <Warning>: Initialize response ready: {"jsonrpc":"2.0","id":"0","result":{"protocolVersion":"2025-06-18","capabilities":{"tools":{}},"serverInfo":{"name":"mcpwikipedia","version":"1.0.0"}}}
Oct 18 13:40:45  mcpwikipedia[1014] <Warning>: Back from ProcessRequest, response is: not Nil
Oct 18 13:40:45  mcpwikipedia[1014] <Warning>: Sending response: {"jsonrpc":"2.0","id":"0","result":{"protocolVersion":"2025-06-18","capabilities":{"tools":{}},"serverInfo":{"name":"mcpwikipedia","version":"1.0.0"}}}
Oct 18 13:40:45  mcpwikipedia[1014] <Warning>: Response sent and flushed

I am certain my app is flushing stdout correctly so I don't understand why mcpo is not starting correctly. As mentioned earlier, this tool works perfectly in LM Studio and Claude Desktop so I know I am implementing the MCP correctly.

Logs & Screenshots

See above.

Additional Information

No response

Originally created by @gkjpettet on GitHub (Oct 18, 2025). Original GitHub issue: https://github.com/open-webui/mcpo/issues/265 ### Check Existing Issues - [x] I have searched the existing issues and discussions. - [x] I am using the latest version of mcpo. ### mcpo Version v1.0 ### Open WebUI Version (if applicable) v0.6.34 ### Operating System macOS Tahoe ### Browser (if applicable) Safari 26.0.1 ### Confirmation - [x] I have read and followed all instructions in `README.md`. - [x] I am using the latest version of **both** MCPO and Open WebUI. - [x] I have included the browser console logs. - [x] I have included the Docker container logs. - [x] I have listed steps to reproduce the bug in detail. ### Expected Behavior I have a custom MCP Server written in Xojo (https://github.com/gkjpettet/mcpwikipedia) that functions through stdout. It works perfectly with LM Studio and Claude Desktop. I am expecting it to be proxied by mcpo to an OpenAPI server. ### Actual Behavior mcpo hangs waiting for application startup. ### Steps to Reproduce 1. I launch my tool (mcpwikipedia) like this: ```bash uvx mcpo --port 51332 -- /Users/garry/mcpservers/mcpwikipedia/mcpwikipedia --useragent="XojoMCPWikipediaSearch" --verbose=true ``` 2. This is the output in the Terminal: ```bash Starting MCP OpenAPI Proxy on 0.0.0.0:51332 with command: stdbuf -o0 /Users/garry/mcpservers/mcpwikipedia/mcpwikipedia --useragent=XojoMCPWikipediaSearch 2025-10-18 13:39:46,162 - INFO - Starting MCPO Server... 2025-10-18 13:39:46,162 - INFO - Name: MCP OpenAPI Proxy 2025-10-18 13:39:46,162 - INFO - Version: 1.0 2025-10-18 13:39:46,162 - INFO - Description: Automatically generated API from MCP Tool Schemas 2025-10-18 13:39:46,162 - INFO - Hostname: Garrys-Mac-Studio.local 2025-10-18 13:39:46,162 - INFO - Port: 51332 2025-10-18 13:39:46,162 - INFO - API Key: Not Provided 2025-10-18 13:39:46,162 - INFO - CORS Allowed Origins: ['*'] 2025-10-18 13:39:46,162 - INFO - Path Prefix: / 2025-10-18 13:39:46,162 - INFO - Root Path: 2025-10-18 13:39:46,162 - INFO - Configuring for a single Stdio MCP Server with command: stdbuf -o0 /Users/garry/mcpservers/mcpwikipedia/mcpwikipedia --useragent=XojoMCPWikipediaSearch 2025-10-18 13:39:46,162 - INFO - Uvicorn server starting... INFO: Started server process [929] INFO: Waiting for application startup. ``` 3. The mcpo server never spins up and I am not able to access the tool via Open API. 4. Turning on verbose mode in my tool shows this: ```bash 2025-10-18 13:40:45,503 - INFO - Uvicorn server starting... INFO: Started server process [1007] INFO: Waiting for application startup. Oct 18 13:40:45 mcpwikipedia[1014] <Warning>: mcpwikipedia starting... Oct 18 13:40:45 mcpwikipedia[1014] <Warning>: mcpwikipedia received: {"method":"initialize","params":{"protocolVersion":"2025-06-18","capabilities":{},"clientInfo":{"name":"mcp","version":"0.1.0"}},"jsonrpc":"2.0","id":0} Oct 18 13:40:45 mcpwikipedia[1014] <Warning>: Processing method: initialize Oct 18 13:40:45 mcpwikipedia[1014] <Warning>: About to handle initialisation Oct 18 13:40:45 mcpwikipedia[1014] <Warning>: {"method":"initialize","params":{"protocolVersion":"2025-06-18","capabilities":{},"clientInfo":{"name":"mcp","version":"0.1.0"}},"jsonrpc":"2.0","id":0} Oct 18 13:40:45 mcpwikipedia[1014] <Warning>: Initialize response ready: {"jsonrpc":"2.0","id":"0","result":{"protocolVersion":"2025-06-18","capabilities":{"tools":{}},"serverInfo":{"name":"mcpwikipedia","version":"1.0.0"}}} Oct 18 13:40:45 mcpwikipedia[1014] <Warning>: Back from ProcessRequest, response is: not Nil Oct 18 13:40:45 mcpwikipedia[1014] <Warning>: Sending response: {"jsonrpc":"2.0","id":"0","result":{"protocolVersion":"2025-06-18","capabilities":{"tools":{}},"serverInfo":{"name":"mcpwikipedia","version":"1.0.0"}}} Oct 18 13:40:45 mcpwikipedia[1014] <Warning>: Response sent and flushed ``` I am certain my app is flushing stdout correctly so I don't understand why mcpo is not starting correctly. As mentioned earlier, this tool works perfectly in LM Studio and Claude Desktop so I know I am implementing the MCP correctly. ### Logs & Screenshots See above. ### Additional Information _No response_
bsakaguchi 2026-10-18 21:11:56 +00:00
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bsakaguchi commented 2026-10-18 21:11:57 +00:00
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@taylorwilsdon commented on GitHub (Oct 18, 2025):

I'm not familiar with xojo but it looks like for macOS, it builds a .app that can be ran. Does the above command actually work with Claude? I cloned your repo but there's no build in there, just src. mcpo is just running stdbuf -o0 /Users/garry/mcpservers/mcpwikipedia/mcpwikipedia --useragent=XojoMCPWikipediaSearch - if you paste that directly into your terminal does the stdio mcp startup?

<!-- gh-comment-id:3418749546 --> @taylorwilsdon commented on GitHub (Oct 18, 2025): I'm not familiar with xojo but it looks like for macOS, it builds a .app that can be ran. Does the above command actually work with Claude? I cloned your repo but there's no build in there, just src. mcpo is just running `stdbuf -o0 /Users/garry/mcpservers/mcpwikipedia/mcpwikipedia --useragent=XojoMCPWikipediaSearch` - if you paste that directly into your terminal does the stdio mcp startup?
bsakaguchi commented 2026-10-18 21:11:57 +00:00
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@gkjpettet commented on GitHub (Oct 18, 2025):

Hi,

I've attached a built binary for macOS (Xojo builds the executable and then a resources folder next to).

I'm using the tool in LM Studio with no problems.

Here's how I call it in LM Studio:

{
  "mcpServers": {
    "mcpwikipedia": {
      "command": "/Users/garry/mcpservers/mcpwikipedia/mcpwikipedia",
      "args": [
        "--useragent",
        "XojoMCPWikipediaSearch"
      ]
    }
  }
}

mcpwikipedia.zip

<!-- gh-comment-id:3418763123 --> @gkjpettet commented on GitHub (Oct 18, 2025): Hi, I've attached a built binary for macOS (Xojo builds the executable and then a resources folder next to). I'm using the tool in LM Studio with no problems. Here's how I call it in LM Studio: ```json { "mcpServers": { "mcpwikipedia": { "command": "/Users/garry/mcpservers/mcpwikipedia/mcpwikipedia", "args": [ "--useragent", "XojoMCPWikipediaSearch" ] } } } ``` [mcpwikipedia.zip](https://github.com/user-attachments/files/22986615/mcpwikipedia.zip)
bsakaguchi commented 2026-10-18 21:11:57 +00:00
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@taylorwilsdon commented on GitHub (May 17, 2026):

I don't think this is a fit for this project, too niche

<!-- gh-comment-id:4472412091 --> @taylorwilsdon commented on GitHub (May 17, 2026): I don't think this is a fit for this project, too niche
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