apache/beam · error · java.lang.IllegalArgumentException

Not a primitive type for field name %s: %s

Error message

Not a primitive type for field name %s: %s

What it means

RowUtils' row/iterable matching walker hits a Schema field whose type is not one of the primitive cases it handles (BYTE, INT16, INT32, INT64, FLOAT, DOUBLE, STRING, BOOLEAN, DATETIME, INSTANT, DECIMAL, BYTES). The default branch is a defensive catch-all: the switch should already have dispatched every primitive, so this means the value produced a processed value only via a path that fell through, i.e. the field's SchemaType was not matched anywhere. It signals an internal type-dispatch failure while validating/capturing a Row's field values.

Source

Thrown at sdks/java/core/src/main/java/org/apache/beam/sdk/values/RowUtils.java:208

          break;
        case DECIMAL:
          processedValue = cases.processDecimal(rowPosition, (BigDecimal) value, this);
          break;
        case FLOAT:
          processedValue = cases.processFloat(rowPosition, (Float) value, this);
          break;
        case DOUBLE:
          processedValue = cases.processDouble(rowPosition, (Double) value, this);
          break;
        case STRING:
          processedValue = cases.processString(rowPosition, (String) value, this);
          break;
        case BOOLEAN:
          processedValue = cases.processBoolean(rowPosition, (Boolean) value, this);
          break;
        default:
          // Shouldn't actually get here, but we need this case to satisfy linters.
          throw new IllegalArgumentException(
              String.format(
                  "Not a primitive type for field name %s: %s", rowPosition.descriptor, fieldType));
      }
      if (processedValue == null) {
        if (!fieldType.getNullable()) {
          throw new IllegalArgumentException(
              String.format("%s is not nullable in  field %s", fieldType, rowPosition.descriptor));
        }
      }
      return processedValue;
    }
  }

  static class FieldOverride {
    FieldOverride(Object overrideValue) {
      this.overrideValue = overrideValue;
    }

View on GitHub (pinned to 12126d8942)

Solutions

1. Check the field's Schema.FieldType; ensure container fields (ARRAY/ITERABLE/MAP) are declared as such so they dispatch to processArray/processMap rather than the primitive switch
2. For LOGICAL_TYPE fields, register the logical type and ensure its base type is a primitive the switch supports
3. Verify the Beam SDK version supports the type in question; upgrade or replace unsupported field types
4. If it seems like an internal bug, file/report to Beam with the schema; the comment says this branch 'shouldn't actually get here'

Example fix

// before (schema field misdeclared)
Schema.Field.of("tags", Schema.FieldType.STRING) // values are actually a list
// after
Schema.Field.of("tags", Schema.FieldType.array(Schema.FieldType.STRING))

Schema.FieldType ft = schema.getField(name).getType();
if (!ft.getTypeName().isPrimitiveType() && !ft.getTypeName().equals(Schema.TypeName.LOGICAL_TYPE)) {
  throw new IllegalArgumentException("Unhandled field type for " + name + ": " + ft);
}

When it happens

Trigger: Calling RowUtils.attachSchema or Row.withSchema-style matching (via processRow/capturedElement/processMap) on a Row whose field has a Schema.TypeName not handled by the switch — typically a LOGICAL_TYPE or newly added type, or a nested container type that reached the leaf matcher instead of the array/map branch.

Common situations: Using a custom logical type (e.g. Joda/Java-time wrappers) or a portable logical type in a schema and then serializing/comparing rows; running code written for an older Beam version against a schema containing types the switch did not know; building rows with mismatched Schema objects where a container type is misdeclared as a leaf.

Understand the failure class

Background: Schema validation failed / invalid input schema: payload rejected because its shape doesn't match the expected schema — this error's family across 28 libraries.

Related errors

• Cannot provide a coder for a Beam Row. Please provide a sche
• Row expected <fieldCount> fields (<fields>). initialized wit
• Null value set on non-nullable field <field>
• Failed to decode Schema due to an error decoding Field proto
• Encountered UNSPECIFIED AtomicType

AI-assisted analysis of apache/beam@12126d8942 (2026-09-13). Data as JSON: /api/errors/1d80fdb06413f10e. Report an issue: GitHub.