apache/beam · error · Exception

Dataflow runner currently supports Python versions

Error message

Dataflow runner currently supports Python versions %s, got %s.%s.
To ignore this requirement and start a job using an unsupported version of Python interpreter, pass --experiment use_unsupported_python_version pipeline option.

What it means

Raised when a pipeline is submitted to Dataflow with a Python interpreter version not in _PYTHON_VERSIONS_SUPPORTED_BY_DATAFLOW. The check runs during client initialization (via __init__), and an escape hatch is offered: the use_unsupported_python_version experiment. This prevents launching jobs whose worker harness image may not exist for that Python version.

Solutions

1. Run the pipeline with a supported Python interpreter, e.g. create a venv with python3.11.
2. Pin the CI/venv Python to a version in _PYTHON_VERSIONS_SUPPORTED_BY_DATAFLOW for the installed Beam release.
3. If you accept the risk, add --experiment=use_unsupported_python_version to pipeline options.
4. Upgrade or downgrade the apache-beam package to a release that supports your Python version.

Example fix

// before
python3.14 -m my_pipeline --runner DataflowRunner
// after
python3.11 -m my_pipeline --runner DataflowRunner
# or, deliberately bypass:
# --experiment=use_unsupported_python_version

import sys
SUPPORTED = {(3, 9), (3, 10), (3, 11), (3, 12)}
if (sys.version_info[0], sys.version_info[1]) not in SUPPORTED and \
   'use_unsupported_python_version' not in (debug_options.experiments or []):
    sys.exit('Unsupported Python for Dataflow: use a supported interpreter')

try:
    client = DataflowApplicationClient(pipeline_options)
except Exception as e:
    if 'supports Python versions' in str(e):
        sys.exit('Re-run with a supported pythonX.Y interpreter')
    raise

When it happens

Trigger: Running Pipeline.run() with DataflowRunner using e.g. a too-new Python (3.14) or an EOL version the Dataflow service no longer supports, without the bypass experiment flag.

Common situations: Local venv upgraded to a new Python release before Beam/Dataflow added support; CI images bumping Python; following Beam docs that lag behind a new Python release.

Understand the failure class

Background: "unsupported platform" / "not supported on this platform" errors: what they mean and how to fix them — this error's family across 47 libraries.

Related errors

• Can not query metrics. Job id is unknown.
• Coder for the GroupByKey operation
• CombineFn.setup and CombineFn.teardown are not supported…
• Could not find element
• Could not translate the internal step name %r.

AI-assisted analysis of apache/beam@12126d8942 (2026-09-13). Data as JSON: /api/errors/3aa15abcc79897c8. Report an issue: GitHub.

Appendix: source

Thrown at sdks/python/apache_beam/runners/dataflow/internal/apiclient.py:1266

def get_response_encoding():
  """Encoding to use to decode HTTP response from Google APIs."""
  return 'utf8'


def _verify_interpreter_version_is_supported(pipeline_options):
  if ('%s.%s' % (sys.version_info[0], sys.version_info[1])
      in _PYTHON_VERSIONS_SUPPORTED_BY_DATAFLOW):
    return

  if 'dev' in beam_version.__version__:
    return

  debug_options = pipeline_options.view_as(DebugOptions)
  if (debug_options.experiments and
      'use_unsupported_python_version' in debug_options.experiments):
    return

  raise Exception(
      'Dataflow runner currently supports Python versions %s, got %s.%s.\n'
      'To ignore this requirement and start a job '
      'using an unsupported version of Python interpreter, pass '
      '--experiment use_unsupported_python_version pipeline option.' % (
          _PYTHON_VERSIONS_SUPPORTED_BY_DATAFLOW,
          sys.version_info[0],
          sys.version_info[1]))

View on GitHub (pinned to 12126d8942)