What causes "error.value.notype" in flowable/flowable-engine?

Pass a concrete Class object as the expected type, e.g. String.class or Object.class if the type is unknown.

flowable/flowable-engine · error · NullPointerException

error.value.notype

Error message

error.value.notype

What it means

ObjectValueExpression wraps a plain object plus the expected type for a deferred EL expression. The constructor throws a NullPointerException (with message 'error.value.notype') when the expected type parameter is null, because a wrapped object expression must declare the type it will coerce to.

Source

Thrown at modules/flowable-engine-common/src/main/java/org/flowable/common/engine/impl/de/odysseus/el/ObjectValueExpression.java:50

	private final TypeConverter converter;
	private final Object object;
	private final Class<?> type;

	/**
	 * Wrap an object into a value expression.
	 * @param converter type converter
	 * @param object the object to wrap
	 * @param type the expected type this object will be coerced in {@link #getValue(ELContext)}.
	 */
	public ObjectValueExpression(TypeConverter converter, Object object, Class<?> type) {
		super();

		this.converter = converter;
		this.object = object;
		this.type = type;
		
		if (type == null) {
			throw new NullPointerException(LocalMessages.get("error.value.notype"));
		}
	}

	/**
	 * Two object value expressions are equal if and only if their wrapped objects are equal.
	 */
	@Override
	public boolean equals(Object obj) {
		if (obj != null && obj.getClass() == getClass()) {
			ObjectValueExpression other = (ObjectValueExpression)obj;
			if (type != other.type) {
				return false;
			}
			return object == other.object || object != null && object.equals(other.object);
		}
		return false;
	}

View on GitHub (pinned to d6d39ce1c6)

Solutions

Pass a concrete Class object as the expected type, e.g. String.class or Object.class if the type is unknown.
If the expected type is computed, default it to Object.class when null before constructing.
Inspect the caller supplying the type (often a framework bridge) and fix where the type is lost.

Example fix

// before
new ObjectValueExpression(converter, object, null)
// after
new ObjectValueExpression(converter, object, expectedType != null ? expectedType : Object.class)

Defensive patterns

Strategy: validation

Validate before calling

if (expectedType == null) {
    throw new IllegalArgumentException("expected type required for ObjectValueExpression");
}
new ObjectValueExpression(converter, object, expectedType);

Type guard

boolean validObjectValueExpressionArgs(Object object, Class<?> type) {
    return type != null;
}

Try / catch

try {
    new ObjectValueExpression(converter, object, type);
} catch (NullPointerException e) {
    // type was null; supply a default
}

Prevention

Always pass a non-null Class as the expected type; default to Object.class when unknown.
Validate framework-bridge code that derives the type from generics/reflection.
Add an assert or precondition before constructing wrapped-object expressions.

When it happens

Trigger: Calling new ObjectValueExpression(converter, object, type) with type == null.

Common situations: Frameworks integrating the EL implementation (e.g. custom ValueExpression factories, CDI/JSF-like integration) passing a null expected type obtained from an untyped API or an unset generic type.

Related errors

AI-assisted analysis of flowable/flowable-engine@d6d39ce1c6 (2026-09-11). Data as JSON: /api/errors/5b627e30e6025506. Report an issue: GitHub.