MT5 build 6296 — Built-in MCP server returns HTTP 401 with Bearer authentication

Mehmet Cakar 2026.11.06 10:52

Hello MetaQuotes team and MQL5 community,

I am experiencing persistent HTTP 401 Unauthorized responses from the built-in MetaTrader 5 MCP server.

Environment

MetaTrader 5 build: 6296
Operating system: Windows
Endpoint: http://127.0.0.1:22346/mcp
Intended MCP client: OpenAI Codex
Authentication: MT5-generated Bearer token

Verified observations

The internal MCP server is enabled and responds at the configured endpoint.
Codex configuration follows the documented http_headers format.
Updating the API key and restarting Codex did not resolve the issue.
Independent PowerShell/.NET MCP initialize requests also receive HTTP 401, with proxies and automatic redirects disabled.
A separate local loopback test confirmed that the HTTP client transmits the Authorization header exactly as configured.
Responses identify Server: MetaTrader5-MCP and include WWW-Authenticate: Bearer realm="MetaTrader5-MCP" .

These independent HTTP results indicate that the authentication failure is reproducible outside Codex. Similar symptoms were reported for earlier builds in this MQL5 forum discussion.

Could you confirm whether build 6296 has a known authentication issue involving generated MCP keys? Does the local server require anything beyond the documented Bearer header? Please advise on a verified remedy that preserves the existing terminal configuration.

No trading operations or security-lock changes were performed during diagnosis. Sanitized results can be provided; API keys and account credentials will not be shared.

Kind regards

Mehmet Cakar