apache/beam · error · InvalidObjectException

Unknown mode for AvroSource

Error message

Unknown mode %s for AvroSource %s

What it means

AvroSource's Java serialization readResolve validates that the persisted mode enum is one of the supported values (SINGLEFILE or FILEPATTERN). An unknown mode means deserialized state is inconsistent, so it throws InvalidObjectException.

Solutions

1. Rebuild the pipeline with a single consistent Beam SDK version
2. Re-create the AvroSource instead of deserializing stale state
3. Clear caches of serialized pipeline artifacts produced by an older Beam version

Example fix

null

try { ObjectInputStream in = ...; AvroSource<?> s = (AvroSource<?>) in.readObject(); } catch (InvalidObjectException e) { /* rebuild source from spec */ }

When it happens

Trigger: Deserializing an AvroSource whose serialized mode field holds a value not in the Mode enum — only possible across incompatible Beam versions or hand-corrupted serialized source state.

Common situations: Pipeline state (e.g. cached source objects or job graphs) serialized by one Beam version and deserialized by another after the Mode enum changed.

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

• bad function
• is not supported
• Could not decode avro record from given bytes
• Could not encode avro from given row
• Error writing row to Avro

AI-assisted analysis of apache/beam@12126d8942 (2026-09-13). Data as JSON: /api/errors/2181a028afc04eba. Report an issue: GitHub.

Appendix: source

Thrown at sdks/java/extensions/avro/src/main/java/org/apache/beam/sdk/extensions/avro/io/AvroSource.java:566

    schema = parser.parse(schemaString);
    schemaLogicalReferenceCache.put(schemaString, schema);
    return schema;
  }

  // Reading the object from Java serialization typically does not go through the constructor,
  // we use readResolve to replace the constructed instance with one which uses the constructor
  // allowing us to intern any schemas.
  @SuppressWarnings("unused")
  private Object readResolve() throws ObjectStreamException {
    switch (getMode()) {
      case SINGLE_FILE_OR_SUBRANGE:
        return new AvroSource<>(
            getSingleFileMetadata(), getMinBundleSize(), getStartOffset(), getEndOffset(), mode);
      case FILEPATTERN:
        return new AvroSource<>(
            getFileOrPatternSpecProvider(), getEmptyMatchTreatment(), getMinBundleSize(), mode);
      default:
        throw new InvalidObjectException(
            String.format("Unknown mode %s for AvroSource %s", getMode(), this));
    }
  }

  /**
   * A {@link Block} of Avro records.
   *
   * @param <T> The type of records stored in the block.
   */
  static class AvroBlock<T> extends Block<T> {

    // The current record in the block. Initialized in readNextRecord.
    private @Nullable T currentRecord;

    // The index of the current record in the block.
    private long currentRecordIndex = 0;

    private final Iterator<?> iterator;

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