greenrobot/EventBus · error · RuntimeException

Failure event class must have a constructor with one paramet

Error message

Failure event class must have a constructor with one parameter of type Throwable

What it means

Thrown as RuntimeException from the AsyncExecutor constructor when failureEventType.getConstructor(Throwable.class) throws NoSuchMethodException. AsyncExecutor's contract: when a RunnableEx passed to execute() throws, AsyncExecutor instantiates the configured failure event class with new FailureEvent(Throwable cause) and posts it. The constructor lookup happens once at AsyncExecutor creation; a failure event without a public single-Throwable constructor makes the mechanism unusable, so construction fails fast.

Source

Thrown at EventBus/src/org/greenrobot/eventbus/util/AsyncExecutor.java:107

    }

    public static AsyncExecutor create() {
        return new Builder().build();
    }

    private final Executor threadPool;
    private final Constructor<?> failureEventConstructor;
    private final EventBus eventBus;
    private final Object scope;

    private AsyncExecutor(Executor threadPool, EventBus eventBus, Class<?> failureEventType, Object scope) {
        this.threadPool = threadPool;
        this.eventBus = eventBus;
        this.scope = scope;
        try {
            failureEventConstructor = failureEventType.getConstructor(Throwable.class);
        } catch (NoSuchMethodException e) {
            throw new RuntimeException(
                    "Failure event class must have a constructor with one parameter of type Throwable", e);
        }
    }

    /** Posts an failure event if the given {@link RunnableEx} throws an Exception. */
    public void execute(final RunnableEx runnable) {
        threadPool.execute(() -> {
            try {
                runnable.run();
            } catch (Exception e) {
                Object event;
                try {
                    event = failureEventConstructor.newInstance(e);
                } catch (Exception e1) {
                    eventBus.getLogger().log(Level.SEVERE, "Original exception:", e);
                    throw new RuntimeException("Could not create failure event", e1);
                }
                if (event instanceof HasExecutionScope) {

View on GitHub (pinned to 0194926b3b)

Solutions

1. Add a public constructor taking exactly one Throwable to the failure event class: public FailureEvent(Throwable throwable) { this.cause = throwable; }
2. In Kotlin: class FailureEvent(val throwable: Throwable) (primary constructor works) or add a secondary constructor
3. Prefer subclassing the provided org.greenrobot.eventbus.util.ThrowableFailureEvent which already defines the required constructor

Example fix

// before
public class MyFailureEvent {
    public String message;
    public MyFailureEvent(String message) { this.message = message; } // no Throwable ctor -> throws
}

// after
public class MyFailureEvent extends org.greenrobot.eventbus.util.ThrowableFailureEvent {
    public MyFailureEvent(Throwable throwable) { super(throwable); }
}

// Verify the failure event contract before building the executor
try {
    failureEventType.getConstructor(Throwable.class);
} catch (NoSuchMethodException e) {
    throw new IllegalStateException(
        failureEventType.getName() + " needs a public constructor taking exactly one Throwable", e);
}
AsyncExecutor exec = AsyncExecutor.builder()
    .eventBus(EventBus.getDefault())
    .failureEventType(failureEventType)
    .buildForScope(this);

When it happens

Trigger: Building an AsyncExecutor via AsyncExecutor.builder().eventBus(bus).failureEventTypeId / .buildForScope(scope) with a failure event class that has no constructor, a multi-arg constructor, a (String) constructor, or a non-public (private/protected/package-private) Throwable constructor.

Common situations: Writing a custom failure event with extra fields and forgetting the Throwable constructor; Kotlin data classes whose only constructor takes additional parameters; making the Throwable constructor private for a factory-pattern class; reusing an arbitrary event class not designed for AsyncExecutor.

Related errors

• Could not create failure event
• It looks like you are using EventBus on Android, make sure t
• Subscriber ${subscriber.getClass()} already registered to ev
• This method may only be called from inside event handling me
• Event may not be null

AI-assisted analysis of greenrobot/EventBus@0194926b3b (2026-08-14). Data as JSON: /api/errors/2584e16ff020c3a3. Report an issue: GitHub.