apache/beam · error · NotImplementedError

Invalid PaneInfoEncoding: %s

Error message

Invalid PaneInfoEncoding: %s

What it means

When encoding a windowed_value.PaneInfo, _PaneInfoCoderImpl picks a PaneInfoEncoding based on which index fields are set (NONE, ONE_INDEX, TWO_INDICES). Any encoding_type outside the known enum has no byte-level representation, so Beam raises NotImplementedError while writing the pane info. This indicates an unrecognized/invalid PaneInfoEncoding value rather than corrupt data.

Source

Thrown at sdks/python/apache_beam/coders/coder_impl.py:1524

          value._timing == windowed_value.PaneInfoTiming.EARLY):
      return PaneInfoEncoding.ONE_INDEX
    else:
      return PaneInfoEncoding.TWO_INDICES

  def encode_to_stream(self, value, out, nested):
    # type: (windowed_value.PaneInfo, create_OutputStream, bool) -> None
    pane_info = value  # cast
    encoding_type = self._choose_encoding(pane_info)
    out.write_byte(pane_info._encoded_byte | (encoding_type << 4))
    if encoding_type == PaneInfoEncoding_FIRST:
      return
    elif encoding_type == PaneInfoEncoding.ONE_INDEX:
      out.write_var_int64(value.index)
    elif encoding_type == PaneInfoEncoding.TWO_INDICES:
      out.write_var_int64(value.index)
      out.write_var_int64(value.nonspeculative_index)
    else:
      raise NotImplementedError('Invalid PaneInfoEncoding: %s' % encoding_type)

  def decode_from_stream(self, in_stream, nested):
    # type: (create_InputStream, bool) -> windowed_value.PaneInfo
    encoded_first_byte = in_stream.read_byte()
    base = windowed_value._BYTE_TO_PANE_INFO[encoded_first_byte & 0xF]
    assert base is not None
    encoding_type = encoded_first_byte >> 4
    if encoding_type == PaneInfoEncoding_FIRST:
      return base
    elif encoding_type == PaneInfoEncoding.ONE_INDEX:
      index = in_stream.read_var_int64()
      if base.timing == windowed_value.PaneInfoTiming.EARLY:
        nonspeculative_index = -1
      else:
        nonspeculative_index = index
    elif encoding_type == PaneInfoEncoding.TWO_INDICES:
      index = in_stream.read_var_int64()
      nonspeculative_index = in_stream.read_var_int64()

View on GitHub (pinned to 12126d8942)

Solutions

1. Construct PaneInfo only via its documented constructor/API so the encoding type is derived correctly
2. Check that all pipeline components use a consistent Beam version (enum values must match)
3. Inspect the PaneInfo object at the failure site and fix its _encoding_type to a valid PaneInfoEncoding member
4. Avoid persisting/monkeypatching PaneInfo internals; rely on windowed_value helpers

Example fix

// before
p = windowed_value.PaneInfo(True, False, rel, 1, None)
p._encoding_type = 99  # invalid
 coder.encode(p)
// after
from apache_beam.coders.coder_impl import PaneInfoEncoding
if p._encoding_type not in (PaneInfoEncoding.NONE,
                            PaneInfoEncoding.ONE_INDEX,
                            PaneInfoEncoding.TWO_INDICES):
    p = windowed_value.PaneInfo(p.is_first, p.is_last, p.timing, p.index, p.nonspeculative_index)
coder.encode(p)

from apache_beam.coders.coder_impl import PaneInfoEncoding
VALID = {PaneInfoEncoding.NONE, PaneInfoEncoding.ONE_INDEX, PaneInfoEncoding.TWO_INDICES}
assert pane._encoding_type in VALID, f'bad encoding type: {pane._encoding_type}'

def has_valid_pane_encoding(pane) -> bool:
    return getattr(pane, '_encoding_type', None) in (
        PaneInfoEncoding.NONE, PaneInfoEncoding.ONE_INDEX, PaneInfoEncoding.TWO_INDICES)

try:
    coder.encode_to_stream(pane, out, nested)
except NotImplementedError as e:
    if 'PaneInfoEncoding' in str(e):
        raise TypeError(f'Invalid PaneInfo object: {e}') from e
    raise

When it happens

Trigger: Encoding a PaneInfo whose _encoding_type attribute is not one of PaneInfoEncoding.NONE/ONE_INDEX/TWO_INDICES — e.g., a PaneInfo constructed manually with a bogus or out-of-range encoding type, or an enum value from a different Beam version.

Common situations: Hand-constructing PaneInfo objects in tests with an invalid encoding; mixing Beam versions where the PaneInfoEncoding enum changed; monkeypatching or deserializing PaneInfo objects that lost their proper enum type.

Understand the failure class

Background: Invalid enum value errors: "Unknown type", "Invalid scope", "must be one of" — when a string is not on the library's allowed list — this error's family across 23 libraries.

Related errors

• Encountered unexpected value for null indicator: '%s'
• Integer value '{value}' is out of the encodable range for Va
• Cannot estimate size for integer value '{value}'. Value is o
• Number of components does not match number of coders.
• Cannot read state-written iterable without state reader.

AI-assisted analysis of apache/beam@12126d8942 (2026-09-13). Data as JSON: /api/errors/38a32e70b0e69633. Report an issue: GitHub.