It's now easier to debug problems with CodeQL code scanning: an optional flag in the Actions workflow file will trigger diagnostic data to be uploaded as an artifact to your Actions run. To do this, you can modify the init step of your Actions workflow:

- name: Initialize CodeQL
  uses: github/codeql-action/init@v1
    debug: true

The data will be uploaded as an Actions artifact named debug-artifacts, attached to the workflow run. Such artifacts contain CodeQL logs, CodeQL databases, and the SARIF files that were produced.

These artifacts will help you when you're debugging problems with CodeQL code scanning. When contacting GitHub support, they might ask for this data too.

Learn more about Troubleshooting the CodeQL workflow.