Error 401 with PAT or Oauth

[benemart]

Hello,

We are trying to connect Open WebUI with the Dremio MCP Server.

We tried both authentication mode : PAT and token Exchange.

The token exchanged works well to access the Dremio API directly on different endpoints so we know it is a valid token.

We have for both authentication modes the same error 401 when trying to connect to the mcp server.

In the mcp-server logs we can see the following:

2025-12-11T17:58:27.362575Z  info [ProjectIdMiddleware] filename=tools.py func_name=dispatch lineno=119 message='Request /mcp body = b\'{"method":"initialize","params":{"protocolVersion":"2025-06-18","capabilities":{},"clientInfo": {"name":"mcp","version":"0.1.0"}},"jsonrpc":"2.0","id":0}\'' 
INFO:  xx.xx.xx.xx:34938 - "POST /mcp HTTP/1.1" 307 Temporary Redirect
2025-12-11T17:58:27.382076Z  info  [ProjectIdMiddleware] filename=tools.py func_name=dispatch lineno=119 message='Request /mcp body = b\'{"method":"initialize","params":{"protocolVersion":"2025-06-18","capabilities":{},"clientInfo":{"name":"mcp","version":"0.1.0"}},"jsonrpc":"2.0","id":0}\'' 
INFO:  xx.xx.xx.xx:34938 - "POST /mcp HTTP/1.1" 401 Unauthorized

Thanks for your help

[vahideozturk]

Hello @benemart I have same issue.
It works when we send requests to the Dremio MCP server via python code from an Jupiter notebook (on an internal server)
But we receive the same errors just like you post when we send requests from another internal server via .net code.
Did you solve the issue ?