## What this fixes
Using dataforseo-mcp-server v2.8.10 via npx in Claude Desktop, the Labs tools `dataforseo_labs_google_ranked_keywords` and `dataforseo_labs_google_domain_rank_overview` fail with `Error: API Error: Invalid Field: 'language_code'. (Code: 40501)`. Other SERP tools in the same server work fine. The server was passing `language_code: "en"` to endpoints that do not accept it.
## The fix
This is not an API bug: a cached old build from npx was the cause. Run `npx -y dataforseo-mcp-server@latest` so npx fetches the current build instead of reusing its cache, and the Labs endpoints stop sending the invalid `language_code` field. The maintainer verified the current build handles the payload correctly, and the reporter confirmed the error is gone after updating.
Source: https://github.com/dataforseo/mcp-server-typescript/issues/45
## Why it happens
The thread above nails the cause, so the fix addresses that directly rather than symptoms. Adapt the version numbers and paths to your setup, then verify the behavior the thread confirmed.
## Source
https://github.com/dataforseo/mcp-server-typescript/issues/45