apache/beam · error · IllegalArgumentException

Failed to print type: {modStructValue}

Error message

Failed to print type: {modStructValue}

What it means

convertModValueProtosToJson builds a struct Value from the modification's fields and prints it to JSON with a JsonFormat printer so TypeCode parsing works. If printing the mod struct Value fails (InvalidProtocolBufferException), IllegalArgumentException "Failed to print type: <modStructValue>" is thrown.

Source

Thrown at sdks/java/io/google-cloud-platform/src/main/java/org/apache/beam/sdk/io/gcp/spanner/changestreams/mapper/ChangeStreamRecordMapper.java:393

  String convertModValueProtosToJson(
      List<com.google.spanner.v1.ChangeStreamRecord.DataChangeRecord.ModValue> modValueProtos,
      List<com.google.spanner.v1.ChangeStreamRecord.DataChangeRecord.ColumnMetadata>
          columnMetadataProtos) {
    com.google.protobuf.Struct.Builder modStructValueBuilder =
        com.google.protobuf.Struct.newBuilder();
    for (com.google.spanner.v1.ChangeStreamRecord.DataChangeRecord.ModValue modValueProto :
        modValueProtos) {
      final String columnName =
          columnMetadataProtos.get(modValueProto.getColumnMetadataIndex()).getName();
      final Value columnValue = modValueProto.getValue();
      modStructValueBuilder.putFields(columnName, columnValue);
    }
    Value modStructValue = Value.newBuilder().setStructValue(modStructValueBuilder.build()).build();
    String modValueJson;
    try {
      modValueJson = this.printer.print(modStructValue);
    } catch (InvalidProtocolBufferException exc) {
      throw new IllegalArgumentException("Failed to print type: " + modStructValue);
    }
    return modValueJson;
  }

  List<Mod> parseProtoMod(
      List<com.google.spanner.v1.ChangeStreamRecord.DataChangeRecord.Mod> modProtos,
      List<com.google.spanner.v1.ChangeStreamRecord.DataChangeRecord.ColumnMetadata>
          columnMetadataProtos) {
    List<Mod> mods = new ArrayList<>();
    for (com.google.spanner.v1.ChangeStreamRecord.DataChangeRecord.Mod modProto : modProtos) {
      final String keysJson =
          convertModValueProtosToJson(modProto.getKeysList(), columnMetadataProtos);
      final String oldValuesJson =
          convertModValueProtosToJson(modProto.getOldValuesList(), columnMetadataProtos);
      final String newValuesJson =
          convertModValueProtosToJson(modProto.getNewValuesList(), columnMetadataProtos);
      Mod mod = new Mod(keysJson, oldValuesJson, newValuesJson);
      mods.add(mod);

View on GitHub (pinned to 12126d8942)

Solutions

1. Upgrade Beam's Google Cloud Platform connector and google.protobuf/spanner libraries to the latest versions.
2. Inspect the printed modStructValue in the message to find the offending Value kind and check the source column's data.
3. Reset/re-read the change stream partition from a good timestamp if the record is corrupt.
4. Sanitize or convert exotic column types (e.g. commit-time/protobuf columns) to standard supported types in the tracked table.

try { printer.print(modStructValue); } catch (InvalidProtocolBufferException e) { /* mod value not renderable */ }

try { modValueJson = printer.print(modStructValue); } catch (InvalidProtocolBufferException e) {
  log.error("Unprintable mod value: {}", modStructValue, e);
}

When it happens

Trigger: A Mod's new/old values struct contains Value protos the printer cannot render — unsupported/unknown kind, malformed nested values from a newer Spanner proto, or corrupted mod data in the change stream record.

Common situations: Change stream records containing exotic value kinds (uninterpreted bytes, new types) on an older connector; corrupted rows in the change stream; proto version drift between Spanner server output and client libraries.

Understand the failure class

Background: json.Marshal / "failed to marshal" errors in Go: why "unsupported type" happens and how to fix it — this error's family across 22 libraries.

Related errors

• Failed to parse DirectedReadOptions from string: + directedR
• Failed to print type: {columnMetadataProto.getType().toStrin
• Failed to parse record into proto: {row}
• Failed to parse the proto bytes to ChangeStreamRecord proto
• Failed to print type: {row}

AI-assisted analysis of apache/beam@12126d8942 (2026-09-13). Data as JSON: /api/errors/cad04725ddff4aa7. Report an issue: GitHub.