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