Unexpected input 'flag-name='

Error:

Unexpected input 'flag-name', valid inputs are ['github-token', 'path-to-lcov', 'parallel', 'parallel-finished', 'coveralls-endpoint', 'base-path']

Config:

      - name: coveralls
        uses: coverallsapp/github-action@master
        with:
          github-token: ${{ secrets.GITHUB_TOKEN }}
          flag-name: ci-results.os-${{ matrix.os }}.node-${{ matrix.node }}.mongo-${{ matrix.mongo }}.redis-${{ matrix.redis }}
          parallel: true

Perhaps I should not use @master ? Should I lock it to a specific version?

Start with the coverallsapp/github-action configuration shown in the workflow and inspect the action's declared inputs for the referenced revision. Check how flag-name is handled across the available action version, then confirm the supported configuration or version guidance that prevents the reported validation error.