apache/pulsar · error · RuntimeException

Unsupported schema type%s

Error message

Unsupported schema type%s

What it means

In createSchema (invoked from setup), the function's declared schema type (SchemaDetails type) hits the default branch of the switch, meaning the runtime has no Schema<T> factory for that schema type enum. Only known schema types (STRING, AVRO, JSON, PROTOBUF, PROTOBUF_NATIVE, AUTO_CONSUME, AUTO_PUBLISH, etc.) are supported.

Source

Thrown at pulsar-functions/instance/src/main/java/org/apache/pulsar/functions/instance/JavaInstanceRunnable.java:1204

                    .withPojo(clazz).build());

            case JSON:
                return JSONSchema.of(SchemaDefinition.<T>builder().withPojo(clazz).build());

            case KEY_VALUE:
                return (Schema<T>) Schema.KV_BYTES();

            case PROTOBUF:
                return ProtobufSchema.ofGenericClass(clazz, new HashMap<>());

            case PROTOBUF_NATIVE:
                return ProtobufNativeSchema.ofGenericClass(clazz, new HashMap<>());

            case AUTO_PUBLISH:
                return (Schema<T>) Schema.AUTO_PRODUCE_BYTES();

            default:
                throw new RuntimeException("Unsupported schema type" + type);
        }
    }

    private static SchemaType getSchemaTypeOrDefault(Record<?> record, Class<?> clazz) {
        if (GenericObject.class.isAssignableFrom(clazz)) {
            return SchemaType.AUTO_CONSUME;
        } else if (byte[].class.equals(clazz)
            || ByteBuf.class.equals(clazz)
            || ByteBuffer.class.equals(clazz)) {
            // if sink uses bytes, we should ignore
            return SchemaType.NONE;
        } else {
            Schema<?> schema = record.getSchema();
            if (schema != null) {
                if (schema.getSchemaInfo().getType() == SchemaType.NONE) {
                    return getDefaultSchemaType(clazz);
                } else {
                    return schema.getSchemaInfo().getType();

View on GitHub (pinned to 820761864e)

Solutions

1. Check the configured schemaType for the function's input/output and change it to a supported type (STRING, JSON, AVRO, PROTOBUF, PROTOBUF_NATIVE, AUTO_CONSUME, AUTO_PUBLISH)
2. Align function worker and broker/client versions so the schema type enum values match; upgrade workers if the type was introduced in a newer Pulsar
3. Use Schema.AUTO_PRODUCE_BYTES() (AUTO_PUBLISH) or AUTO_CONSUME semantics explicitly instead of a custom type string
4. Redeploy the function after correcting the schema configuration

Example fix

// before (function submit)
--output-schema-type KEY_VALUE
// after
--output-schema-type JSON   # or AVRO / STRING / AUTO_PUBLISH as supported

Set<String> supported = Set.of("STRING","JSON","AVRO","PROTOBUF","PROTOBUF_NATIVE","AUTO_CONSUME","AUTO_PUBLISH","BOOLEAN","INT8","INT16","INT32","INT64","FLOAT32","FLOAT64","KEY_VALUE");
if (!supported.contains(details.getOutputSchemaType())) {
    throw new IllegalArgumentException("Unsupported schema type: " + details.getOutputSchemaType());
}

try { deployFunction(); }
catch (RuntimeException e) {
  if (e.getMessage().startsWith("Unsupported schema type")) {
    log.error("Switch to a supported schema type or upgrade function workers", e);
  }
}

When it happens

Trigger: FunctionDetails carries a schemaType value the instance runtime doesn't recognize — typically a newer/older Pulsar SchemaType enum crossing a version boundary, or a custom/legacy type (e.g. a key-value or auto type) configured for a component that maps to no case in this switch.

Common situations: Deploying a function submitted by a newer broker/client to older function workers (schema type added later); scripting function config with a raw schemaType string that mismatches the enum; using AUTO_PRODUCE/AUTO_CONSUME on an unsupported component position.

Related errors

• Schema should not be null.
• Schema type mismatch ${typeArg} vs ${schemaTypeArg}
• Failed to add schema to an active topic with empty(BYTES) sc
• Error during schema compatibility check with strategy ${stra
• Retrieve schema instance from schema info for type '${schema

AI-assisted analysis of apache/pulsar@820761864e (2026-09-06). Data as JSON: /api/errors/230312f99b3a52c4. Report an issue: GitHub.