CodeQL matrix language / config mismatch in CI

By Kaveh Alemi·Latchkey

CodeQL workflows commonly fan out one job per language via a matrix. If the matrix value does not match the languages input, or a build step runs for the wrong matrix leg, analysis fails or scans nothing.

What this error means

A matrix leg fails because init receives an unexpected language, a compiled-language build runs during an interpreted leg, or the same language is analyzed twice with conflicting configs.

Error: Did not recognize the following languages: 'golang'
Supported languages are: actions, cpp, csharp, go, java, javascript-typescript, python, ruby, swift

Common causes

The matrix value is not a valid CodeQL language

Using an alias like golang or typescript instead of the supported identifier (go, javascript-typescript) makes init reject it.

A build step runs for the wrong matrix leg

A compiled-language build (Maven, Gradle) runs on the Python or JavaScript leg, wasting time or failing that job.

How to fix it

Align matrix values with init and gate builds

1. Use the exact supported language identifiers in the matrix.
2. Pass languages: ${{ matrix.language }} so init matches the leg.
3. Guard compiled-language build steps with an if on the matrix language.

strategy:
  matrix:
    language: [java, javascript-typescript, python]
steps:
  - uses: github/codeql-action/init@v3
    with:
      languages: ${{ matrix.language }}
  - if: matrix.language == 'java'
    run: mvn -B clean compile

Use the canonical language identifiers

Replace aliases: go (not golang), javascript-typescript (not typescript), csharp (not c#).

How to prevent it

• List only supported CodeQL language identifiers in the matrix.
• Drive init and build gating from the matrix value.
• Keep one language per matrix leg to isolate failures.

Frequently asked questions

Related guides

References

• GitHub Actions documentation