apache/beam · warning

Skipping proto generation as they are already generated.

Error message

Skipping proto generation as they are already generated.

What it means

Beam's generate_protos_first target checks whether generated *_pb2.py files already exist; if so it warns that proto regeneration is skipped and returns without invoking gen_protos.py. It ensures stale/absent regeneration is explicit rather than silently re-running codegen.

Solutions

1. If you changed .proto files, delete generated files (find apache_beam -name '*_pb2*.py' -delete and *_pb2_grpc.py) and re-run generation.
2. Run gen_protos.py directly with --force to regenerate regardless of existing outputs.
3. If skipping is intended, ignore the warning — generated protos are already present.

Example fix

// before
$ python setup.py generate_protos_first   # warns, skips
// after
$ find apache_beam -name '*_pb2*.py' -delete
$ python setup.py generate_protos_first

import glob, subprocess, sys, os
if glob.glob('apache_beam/**/*_pb2.py', recursive=True):
    subprocess.run([sys.executable, 'gen_protos.py', '--force'], check=True)  # regenerate after .proto edits

When it happens

Trigger: Running the proto-generation setup target (generate_protos_first) when the sdks/python directory already contains generated _pb2.py files, so the codegen subprocess is bypassed.

Common situations: Re-running builds after a partial codegen; developers who edited .proto files but still see old generated code because pb2 files exist and generation is skipped.

Related errors

• protobuf files are not generated. Please generate pb2 files
• Could not generate external transform wrappers due to error
• Could not generate protos due to error
• Cannot convert from nanoseconds to microseconds because…
• cannot convert to micro seconds

AI-assisted analysis of apache/beam@12126d8942 (2026-09-13). Data as JSON: /api/errors/710ca9052d795e97. Report an issue: GitHub.

Appendix: source

Thrown at sdks/python/setup.py:251

  try:
    # Pyproject toml build happens in isolated environemnts. In those envs,
    # gen_protos is unable to get imported. so we run a subprocess call.
    cwd = os.path.abspath(os.path.dirname(__file__))
    # when pip install <>.tar.gz gets called, if gen_protos.py is not available
    # in the sdist,then the proto files would have already been generated. So we
    # skip proto generation in that case.
    if not os.path.exists(os.path.join(cwd, 'gen_protos.py')):
      # make sure we already generated protos
      pb2_files = list(
          find_by_ext(
              os.path.join(cwd, 'apache_beam', 'portability', 'api'),
              '_pb2.py'))
      if not pb2_files:
        raise RuntimeError(
            'protobuf files are not generated. '
            'Please generate pb2 files')

      warnings.warn('Skipping proto generation as they are already generated.')
      return
    out = subprocess.run(
        [sys.executable, os.path.join(cwd, 'gen_protos.py'), '--no-force'],
        capture_output=True,
        check=True)
    print(out.stdout)
  except subprocess.CalledProcessError as err:
    raise RuntimeError('Could not generate protos due to error: %s', err.stderr)


def copy_tests_from_docs():
  python_root = os.path.abspath(os.path.dirname(__file__))
  docs_src = os.path.normpath(
      os.path.join(
          python_root, '../../website/www/site/content/en/documentation/sdks'))
  docs_dest = os.path.normpath(
      os.path.join(python_root, 'apache_beam/yaml/docs'))
  if os.path.exists(docs_src):

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