apache/pulsar · error · SchemaSerializationException

This method is not supported

Error message

This method is not supported

What it means

AbstractSchema's default validate(ByteBuf) implementation is a sentinel: base schema classes that do not support byte-level validation throw this SchemaSerializationException when validate() is invoked. It indicates the schema in use does not implement message validation.

Source

Thrown at pulsar-client/src/main/java/org/apache/pulsar/client/impl/schema/AbstractSchema.java:41

import org.apache.pulsar.client.api.Schema;
import org.apache.pulsar.client.api.SchemaSerializationException;

public abstract class AbstractSchema<T> implements Schema<T> {

    /**
     * Check if the message read able length length is a valid object for this schema.
     *
     * <p>The implementation can choose what its most efficient approach to validate the schema.
     * If the implementation doesn't provide it, it will attempt to use {@link #decode(ByteBuf)}
     * to see if this schema can decode this message or not as a validation mechanism to verify
     * the bytes.
     *
     * @param byteBuf the messages to verify
     * @return true if it is a valid message
     * @throws SchemaSerializationException if it is not a valid message
     */
    void validate(ByteBuf byteBuf) {
        throw new SchemaSerializationException("This method is not supported");
    };

    /**
     * Decode a byteBuf into an object using the schema definition and deserializer implementation
     * <p>Do not modify reader/writer index of ByteBuf so, it can be reused to access correct data.
     *
     * @param byteBuf
     *            the byte buffer to decode
     * @return the deserialized object
     */
    public abstract T decode(ByteBuf byteBuf);
    /**
     * Decode a byteBuf into an object using a given version.
     *
     * @param byteBuf
     *            the byte array to decode
     * @param schemaVersion
     *            the schema version to decode the object. null indicates using latest version.

View on GitHub (pinned to 820761864e)

Solutions

1. Override validate(ByteBuf) in your custom schema to actually check the payload.
2. Do not call validate() on schemas that declare no validation support; guard with a capability check.
3. Use a concrete schema type (e.g. struct schemas) that implements validation if you need it.

Example fix

// before
Schema<MyType> s = new AbstractSchema<MyType>() { public MyType decode(byte[] b){...} };
consumer.validate(msg);
// after
Schema<MyType> s = new AbstractSchema<MyType>() {
  public MyType decode(byte[] b){...}
  public void validate(ByteBuf buf){ decode(buf.duplicate()); }
};
consumer.validate(msg);

boolean supportsValidation(Schema<?> s) {
  try { s.getClass().getDeclaredMethod("validate", io.netty.buffer.ByteBuf.class); return true; }
  catch (NoSuchMethodException e) { return false; }
}

try { schema.validate(buf); } catch (SchemaSerializationException e) { /* schema does not support validation; skip or decode manually */ }

When it happens

Trigger: Calling validate(ByteBuf) (directly or via Consumer/Producer paths that verify incoming messages) on a schema extending AbstractSchema without overriding validate, e.g. schemas built from generic decoders that never implement validation.

Common situations: Custom schema implementations that forget to override validate(); code paths that call validate() unconditionally on schemas known not to support it; enabling features like consumer-side schema validation with a barebones schema.

Related errors

• Not implemented for ${this.getClass}
• Size of data received by BooleanSchema is not 1
• Size of data received by ByteSchema is not 1
• Size of data received by DoubleSchema is not 8
• Can not enable for all producers but denies for replicators,

AI-assisted analysis of apache/pulsar@820761864e (2026-09-06). Data as JSON: /api/errors/4de8431f213c857b. Report an issue: GitHub.