flowable/flowable-engine · error · PropertyNotFoundException

PropertyNotFoundException

Error message

PropertyNotFoundException

What it means

ArrayELResolver.checkBounds throws PropertyNotFoundException when an EL expression indexes into an array with an out-of-range index (negative or >= array length). This is the EL resolver's way of surfacing an ArrayIndexOutOfBoundsException as a standard EL exception during getType, setValue, or isReadOnly resolution.

Source

Thrown at modules/flowable-engine-common/src/main/java/org/flowable/common/engine/impl/javax/el/ArrayELResolver.java:306

	@Override
	public Class<?> getCommonPropertyType(ELContext context, Object base) {
		return isResolvable(base) ? Integer.class : null;
	}

	/**
	 * Test whether the given base should be resolved by this ELResolver.
	 * 
	 * @param base
	 *            The bean to analyze.
	 * @return base != null && base.getClass().isArray()
	 */
	private final boolean isResolvable(Object base) {
		return base != null && base.getClass().isArray();
	}

	private static void checkBounds(Object base, int idx) {
		if (idx < 0 || idx >= Array.getLength(base)) {
			throw new PropertyNotFoundException(new ArrayIndexOutOfBoundsException(idx).getMessage());
		}
	}

	private static int coerce(Object property) {
		if (property instanceof Number) {
			return ((Number) property).intValue();
		}
		if (property instanceof Character) {
			return (Character) property;
		}
		if (property instanceof Boolean) {
			return (Boolean) property ? 1 : 0;
		}
		if (property instanceof String) {
			try {
				return Integer.parseInt((String) property);
			} catch (NumberFormatException e) {
				throw new IllegalArgumentException("Cannot parse array index: " + property, e);

View on GitHub (pinned to d6d39ce1c6)

Solutions

1. Log/inspect the array length at evaluation time and fix the expression's index to be within 0..length-1.
2. Guard the expression with a bounds check, e.g. ${myArray.length > 5 ? myArray[5] : ''}, or use a List instead of an array (ListELResolver returns null for out-of-range instead of throwing).
3. If the index comes from a variable, validate/clamp it before evaluation.

Example fix

// before
String first = (String) engine.eval("${items[0]}", itemsIsEmptyContext);
// after
String expr = items.length > 0 ? "${items[0]}" : "${null}"; // or guard in the EL expression itself

if (idx < 0 || idx >= arr.length) throw new IllegalArgumentException("index " + idx + " out of bounds for array of length " + arr.length);

try { value = resolver.getValue(ctx, base, idx); } catch (PropertyNotFoundException e) { /* fallback to default */ }

When it happens

Trigger: Evaluating an EL expression like ${myArray[5]} where myArray has fewer than 6 elements, or a negative index such as ${myArray[-1]}, or a coerced String index like 'idx' that resolves outside 0..length-1.

Common situations: Expressions referencing array positions computed from loop counters or list sizes in process/BPMN expressions; off-by-one indexing; arrays shrunk by refactoring while templates still reference old fixed indexes.

Related errors

• Cannot parse array index:
• Cannot coerce property to array index:
• error.coerce.type
• ' + token.getImage() + '
• error.identifier.method.notamethod

AI-assisted analysis of flowable/flowable-engine@d6d39ce1c6 (2026-09-11). Data as JSON: /api/errors/18d88720b2261135. Report an issue: GitHub.