apache/pulsar · error · IllegalArgumentException

The input schema is not of type 'org.apache.avro.Schema'.

Error message

The input schema is not of type 'org.apache.avro.Schema'.

What it means

NativeAvroBytesSchema's constructor validates that the object passed in is an org.apache.avro.Schema instance. If it is anything else (a String, a POJO, a Class, etc.) it throws IllegalArgumentException immediately at schema construction.

Source

Thrown at pulsar-client/src/main/java/org/apache/pulsar/client/impl/schema/NativeAvroBytesSchema.java:64

        this.nativeSchema = schema;
        Map<String, String> properties = new HashMap<>();
        properties.put(ALWAYS_ALLOW_NULL, "true");
        properties.put(JSR310_CONVERSION_ENABLED, "false");
        this.schemaInfo = SchemaInfo.builder()
            .name("")
            .schema(schema.toString().getBytes(StandardCharsets.UTF_8))
            .properties(properties)
            .type(SchemaType.AVRO)
            .build();
    }

    public NativeAvroBytesSchema(Object schema) {
        this(validateSchema(schema));
    }

    private static org.apache.avro.Schema validateSchema (Object schema) {
        if (!(schema instanceof org.apache.avro.Schema)) {
            throw new IllegalArgumentException("The input schema is not of type 'org.apache.avro.Schema'.");
        }
        return (org.apache.avro.Schema) schema;
    }

    @Override
    public byte[] encode(byte[] message) {
        return message;
    }

    /* decode should not be used because this is a Schema to be used on the Producer side */
    @Override
    public byte[] decode(byte[] bytes, byte[] schemaVersion) {
        throw new UnsupportedOperationException();
    }

    @Override
    public SchemaInfo getSchemaInfo() {
        return schemaInfo;

View on GitHub (pinned to 820761864e)

Solutions

Parse the raw JSON into an Avro Schema first: new Schema.Parser().parse(schemaJson)
Ensure the variable's compile-time type is org.apache.avro.Schema
Use Schema.AVRO(SomePojo.class) if you want a POJO-driven schema instead of NativeAvroBytesSchema

Example fix

// before
NativeAvroBytesSchema s = new NativeAvroBytesSchema("{"type":"record"...}");
// after
org.apache.avro.Schema avro = new Schema.Parser().parse("{"type":"record"...}");
NativeAvroBytesSchema s = new NativeAvroBytesSchema(avro);

Defensive patterns

Strategy: type-guard

Validate before calling

if (!(obj instanceof org.apache.avro.Schema)) { throw new IllegalArgumentException("must be an org.apache.avro.Schema"); }

Type guard

boolean isAvroSchema(Object o) { return o instanceof org.apache.avro.Schema; }

Try / catch

try { new NativeAvroBytesSchema<>(obj); } catch (IllegalArgumentException e) { /* parse schema from JSON and retry */ }

Prevention

Parse schema strings with new Schema.Parser().parse(...) before constructing
Keep variables typed as org.apache.avro.Schema
Prefer Schema.AVRO(Pojo.class) unless you specifically need native bytes passthrough

When it happens

Trigger: new NativeAvroBytesSchema(someString) or passing a Pulsar SchemaInfo/other schema object instead of a real org.apache.avro.Schema (e.g. Schema.Parser().parse(...) result).

Common situations: Mixing up Avro schema JSON text with a parsed Schema object; passing a SchemaDefinition or generic Object from generic API; refactors that changed the schema variable's type.

Related errors

AI-assisted analysis of apache/pulsar@820761864e (2026-09-06). Data as JSON: /api/errors/f08bb7c7898b86d9. Report an issue: GitHub.