hibernate/hibernate-orm · error · JDBCException

Unable to set BLOB bytes after creation

Error message

Unable to set BLOB bytes after creation

What it means

BlobAndClobCreator.createBlob(byte[]) (the contextual LOB creator) first creates an empty java.sql.Blob via Connection.createBlob() and then fills it with blob.setBytes(1, bytes). If the driver's Blob implementation rejects setBytes - throws SQLException - Hibernate wraps it as JDBCException('Unable to set BLOB bytes after creation') keeping the cause.

Source

Thrown at hibernate-core/src/main/java/org/hibernate/engine/jdbc/env/internal/BlobAndClobCreator.java:75

	 * @return The created BLOB reference.
	 */
	Blob createBlob() {
		return lobCreationContext.fromContext( CREATE_BLOB_CALLBACK );
	}

	/**
	 * Create a {@link Blob} object after reading a {@code byte[]}
	 * array from a JDBC {@link ResultSet}.
	 */
	@Override
	public Blob createBlob(byte[] bytes) {
		final Blob blob = createBlob();
		try {
			blob.setBytes( 1, bytes );
			return blob;
		}
		catch ( SQLException e ) {
			throw new JDBCException( "Unable to set BLOB bytes after creation", e );
		}
	}

	/**
	 * Create a {@link Blob} object after reading an {@link InputStream}
	 * from a JDBC {@link ResultSet}.
	 *
	 * @implNote
	 * It's very inefficient to use JDBC LOB locator creation to create
	 * a LOB with the contents of the given stream, since that requires
	 * reading the whole stream. So instead just wrap the given stream,
	 * just like what {@link NonContextualLobCreator} does.
	 */
	@Override
	public Blob createBlob(InputStream stream, long length) {
		return NonContextualLobCreator.INSTANCE.createBlob( stream, length );
	}

View on GitHub (pinned to fad1729dce)

Solutions

1. Disable contextual LOB creation: hibernate.jdbc.lob.non_contextual_creation=true - Hibernate then wraps the byte[] directly instead of using Connection.createBlob()
2. Upgrade the JDBC driver to one whose createBlob()/setBytes() works
3. Ensure the LobCreator is used while its connection is open (bind LOB creation to the transaction/session lifetime)

Example fix

# before
# contextual LOB creation active, driver setBytes fails

# after
<property name="hibernate.jdbc.lob.non_contextual_creation" value="true"/>

// opt out of contextual LOB creation for drivers with weak Blob support
if ( driverHasWeakLobSupport ) {
    settings.put(AvailableSettings.NON_CONTEXTUAL_LOB_CREATION, true);
}

try {
    return lobCreator.createBlob(bytes);
} catch (JDBCException e) {
    // fallback: wrap bytes directly, no driver LOB involvement
    Blob b = new SerialBlob(bytes);
    return b;
}

When it happens

Trigger: Contextual LOB creation is enabled and the JDBC driver's Connection.createBlob() returns a Blob whose setBytes(long, byte[]) fails: operation unsupported by the driver, the LOB freed before write, or the creating connection already closed when the write occurs.

Common situations: Drivers with read-only or locator-backed Blob implementations (some Oracle/DB2 modes, thin drivers behind proxies); LobCreator used after the transaction/connection closed; large byte arrays exceeding driver LOB limits.

Related errors

• Could not create JDBC Blob
• Unable to set CLOB string after creation
• Start position 1-based; must be 1 or more.
• Length must be great-than-or-equal to zero.
• Start position [<start>] cannot exceed overall CLOB length [

AI-assisted analysis of hibernate/hibernate-orm@fad1729dce (2026-08-22). Data as JSON: /api/errors/46918b1de7601d27. Report an issue: GitHub.