What causes "Invalid priority value for (must be an integer)" in flowable/flowable-engine?

Set priority to a valid integer string, e.g. "5" or "-1"

flowable/flowable-engine · error · IllegalArgumentException

Invalid priority value for <channelDefinition> (must be an i

Error message

Invalid priority value for <channelDefinition> (must be an integer)

What it means

The channel definition's priority attribute is resolved as a String and must parse to an Integer for the Rabbit listener consumer priority. If it has text but is not a valid integer, resolvePriority throws this IllegalArgumentException (wrapping the NumberFormatException).

Source

Thrown at modules/flowable-event-registry-spring/src/main/java/org/flowable/eventregistry/spring/rabbit/RabbitChannelDefinitionProcessor.java:213

        } else if (resolvedValueToUse instanceof Queue) {
            result.add(((Queue) resolvedValueToUse).getName());
        } else if (resolvedValueToUse instanceof Iterable) {
            for (Object object : (Iterable<?>) resolvedValueToUse) {
                resolveQueues(object, result, channelDefinition);
            }
        } else {
            throw new IllegalArgumentException(
                "Channel definition " + channelDefinition + " cannot resolve " + resolvedValue + " as a String[] or a String or a Queue");
        }
    }

    protected Integer resolvePriority(RabbitInboundChannelModel channelDefinition) {
        String priority = resolve(channelDefinition.getPriority());
        if (StringUtils.hasText(priority)) {
            try {
                return Integer.valueOf(priority);
            } catch (NumberFormatException ex) {
                throw new IllegalArgumentException("Invalid priority value for " +
                    channelDefinition + " (must be an integer)", ex);
            }
        } else {
            return null;
        }
    }

    protected RabbitAdmin resolveAdmin(RabbitInboundChannelModel channelDefinition) {
        String rabbitAdmin = resolve(channelDefinition.getAdmin());
        if (StringUtils.hasText(rabbitAdmin)) {
            Assert.state(this.beanFactory != null, "BeanFactory must be set to resolve RabbitAdmin by bean name");
            try {
                return this.beanFactory.getBean(rabbitAdmin, RabbitAdmin.class);
            } catch (NoSuchBeanDefinitionException ex) {
                throw new IllegalArgumentException("Could not register rabbit listener endpoint on [" +
                    channelDefinition + "], no " + RabbitAdmin.class.getSimpleName() + " with id '" +
                    rabbitAdmin + "' was found in the application context", ex);
            }

View on GitHub (pinned to d6d39ce1c6)

Solutions

Set priority to a valid integer string, e.g. "5" or "-1"
Check the resolved string for hidden whitespace/units and trim it
Remove the priority attribute entirely if you want the default (resolvePriority returns null when blank)
Validate numeric fields at configuration-load time

Example fix

// before
channelDefinition.setPriority("high");
// after
channelDefinition.setPriority("5");

Defensive patterns

Strategy: validation

Validate before calling

String priority = channelDefinition.getPriority();
if (priority != null && !priority.isBlank()) {
    try { Integer.valueOf(priority.trim()); }
    catch (NumberFormatException e) { throw new IllegalArgumentException("priority must be an integer: " + priority); }
}

Try / catch

try {
    processor.process(definition);
} catch (IllegalArgumentException ex) {
    if (ex.getMessage().contains("priority")) {
        log.error("Fix priority in {}: {}", definition, ex.getMessage());
    }
    throw ex;
}

Prevention

Store priority as an integer string without whitespace or units
Validate numeric fields when loading channel definitions
Leave priority blank rather than using symbolic names like 'high'

When it happens

Trigger: Setting channelDefinition.setPriority("high") or any non-numeric string like "10x", "default", or an expression resolving to non-numeric text, so Integer.valueOf fails.

Common situations: Configuring priority with a word instead of a number; placeholders resolving to values with whitespace or units ("5 "); copying priority formats from other systems (e.g. '0-9 labels'); typos.

Understand the failure class

Background: "Invalid value" and "allowed values are" config errors: what your library rejected and how to fix it — this error's family across 41 libraries.

Related errors

AI-assisted analysis of flowable/flowable-engine@d6d39ce1c6 (2026-09-11). Data as JSON: /api/errors/d9a2accab0b6d475. Report an issue: GitHub.