flowable/flowable-engine · error · FlowableIllegalArgumentException

Entity cannot be null.

Error message

Entity cannot be null.

What it means

FlowableEntityExceptionEventImpl is a FlowableEntityEventImpl that additionally carries the Throwable that caused the event (e.g. for ENTITY_CREATED-with-exception style error propagation). It inherits the non-null entity contract: constructing it without an entity throws FlowableIllegalArgumentException, even though the cause itself may legitimately be null per this constructor.

Solutions

1. Pass a non-null entity to the constructor; resolve or substitute the entity before creating the event.
2. If only the exception matters, use a plain FlowableEventImpl/FlowableExceptionEvent event type not bound to an entity.
3. Guard the construction site with a null check and log-and-skip when the entity is absent.

Example fix

// before
events.add(new FlowableEntityExceptionEventImpl(entityRef.get(), type, cause)); // get() may be null

// after
if (entityRef.get() != null) {
    events.add(new FlowableEntityExceptionEventImpl(entityRef.get(), type, cause));
}

if (entity == null) {
    log.warn("Skipping exception event dispatch: no entity available");
    return;
}
events.add(new FlowableEntityExceptionEventImpl(entity, type, cause));

boolean canBuildExceptionEvent(Object entity) { return entity != null; }

try {
    events.add(new FlowableEntityExceptionEventImpl(entity, type, cause));
} catch (FlowableIllegalArgumentException e) {
    log.error("Cannot create entity exception event: entity is null", e);
    throw e;
}

When it happens

Trigger: Calling new FlowableEntityExceptionEventImpl(null, type, cause) directly; event-building code in custom error handling where the entity reference is null when the failure event is created.

Common situations: Custom exception/listener plumbing that creates failure events from a null entity (e.g. entity failed to load); test harnesses constructing exception events without an entity; integration code where an earlier lookup returned null.

Related errors

• Entity cannot be null.
• type is null
• Entity cannot be null.
• Entity cannot be null.
• Entity cannot be null.

AI-assisted analysis of flowable/flowable-engine@d6d39ce1c6 (2026-09-11). Data as JSON: /api/errors/97400bec58d5f5e3. Report an issue: GitHub.

Appendix: source

Thrown at modules/flowable-engine-common/src/main/java/org/flowable/common/engine/impl/event/FlowableEntityExceptionEventImpl.java:34

import org.flowable.common.engine.api.delegate.event.FlowableEngineEntityEvent;
import org.flowable.common.engine.api.delegate.event.FlowableEngineEventType;
import org.flowable.common.engine.api.delegate.event.FlowableEvent;
import org.flowable.common.engine.api.delegate.event.FlowableExceptionEvent;

/**
 * Base class for all {@link FlowableEvent} implementations, represents an exception occurred, related to an entity.
 * 
 * @author Frederik Heremans
 */
public class FlowableEntityExceptionEventImpl extends FlowableEngineEventImpl implements FlowableEngineEntityEvent, FlowableExceptionEvent {

    protected Object entity;
    protected Throwable cause;

    public FlowableEntityExceptionEventImpl(Object entity, FlowableEngineEventType type, Throwable cause) {
        super(type);
        if (entity == null) {
            throw new FlowableIllegalArgumentException("Entity cannot be null.");
        }
        this.entity = entity;
        this.cause = cause;
    }

    @Override
    public Object getEntity() {
        return entity;
    }

    @Override
    public Throwable getCause() {
        return cause;
    }
}

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