apache/beam · error · IllegalArgumentException

The parameter list: does not match the expected fields

Error message

The parameter list: %s does not match the expected fields: %s

What it means

ThriftSchema.restoreThriftObject reconstructs a thrift instance from an array of field values built by schema-based creation. If the number of supplied parameters differs from the number of expected thrift fields, an IllegalArgumentException with this message is thrown, indicating the schema used to produce the values diverged from the thrift class metadata.

Solutions

  1. Regenerate thrift classes and refresh all Beam Schemas so field counts match
  2. Ensure Rows read from older data are migrated to the current thrift schema before reconstruction
  3. Check the message's parameter list vs expected fields to identify which side is stale

Example fix

// before
Row row = rowWithOldSchema; // 3 fields, thrift class now has 4
ThriftRecord r = creator.create(ThriftRecord.class, row);
// after
Schema current = ThriftSchema.provider().schemaFor(TypeDescriptor.of(ThriftRecord.class));
Row migrated = migrateRowToSchema(row, current);
ThriftRecord r = creator.create(ThriftRecord.class, migrated);
Defensive patterns

Strategy: validation

Validate before calling

Schema inferred = ThriftSchema.provider().schemaFor(TypeDescriptor.of(ThriftRecord.class)); if (row.getSchema().getFieldCount() != inferred.getFieldCount()) { throw new IllegalArgumentException("row schema stale vs thrift class"); }

Try / catch

try { ThriftRecord r = creator.create(ThriftRecord.class, row); } catch (IllegalArgumentException e) { LOG.error("row/thrift field count mismatch: {}", e.getMessage()); throw e; }

Prevention

When it happens

Trigger: Creating a thrift object through the Beam Schema type creator when the Row/parameter list has more or fewer fields than the TBase's registered field metadata — typically after the IDL changed while cached schemas/rows were not refreshed.

Common situations: Adding or removing a thrift field and replaying old Rows; running a pipeline with a stale thrift class version on one side; hand-constructed Object[] passed to the schema type creator.

Related errors

AI-assisted analysis of apache/beam@12126d8942 (2026-09-13). Data as JSON: /api/errors/089cb9d046766df2. Report an issue: GitHub.

Appendix: source

Thrown at sdks/java/io/thrift/src/main/java/org/apache/beam/sdk/io/thrift/ThriftSchema.java:296

    final Map<String, TFieldIdEnum> fields =
        fieldDescriptors.keySet().stream()
            .collect(Collectors.toMap(TFieldIdEnum::getFieldName, Function.identity()));

    return schema.getFields().stream()
        .map(Schema.Field::getName)
        .map(fields::get)
        .collect(
            Collectors.toMap(
                Function.identity(),
                fieldDescriptors::get,
                ThriftSchema::throwingCombiner,
                LinkedHashMap::new));
  }

  private <FieldT extends TFieldIdEnum, T extends TBase<T, FieldT>> T restoreThriftObject(
      Class<?> targetClass, Map<FieldT, FieldMetaData> fields, Object[] params) {
    if (params.length != fields.size()) {
      throw new IllegalArgumentException(
          String.format(
              "The parameter list: %s does not match the expected fields: %s",
              Arrays.toString(params), fields.keySet()));
    }
    try {
      @SuppressWarnings("unchecked")
      final T thrift = (T) targetClass.getDeclaredConstructor().newInstance();
      final Iterator<Entry<FieldT, FieldMetaData>> iter = fields.entrySet().iterator();
      Stream.of(params).forEach(param -> setThriftField(thrift, iter.next(), param));
      return thrift;
    } catch (Exception e) {
      throw new IllegalStateException(e);
    }
  }

  private <FieldT extends TFieldIdEnum, T extends TBase<T, FieldT>> void setThriftField(
      T thrift, Entry<FieldT, FieldMetaData> fieldDescriptor, Object value) {
    final FieldT field = fieldDescriptor.getKey();

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