flowable/flowable-engine · error · ActivitiException

Cannot deploy process definition

Error message

Cannot deploy process definition '%s': there multiple message event subscriptions for the message with name '%s'.

What it means

When deploying, every message start event in the process creates a message event subscription. If a single process definition declares multiple start events subscribed to the same message name, the deployment is rejected because subscriptions would be ambiguous.

Solutions

Give each message start event a distinct message name (or distinct message element)
Remove the duplicate message start event
Use one start event with multiple conditional paths instead of multiple identical message starts

Example fix

<!-- before -->
<message id="msgOrder" name="orderMessage"/>
<startEvent id="s1"><messageEventDefinition messageRef="msgOrder"/></startEvent>
<startEvent id="s2"><messageEventDefinition messageRef="msgOrder"/></startEvent>
<!-- after -->
<message id="msgOrder" name="orderMessage"/>
<message id="msgCancel" name="cancelMessage"/>
<startEvent id="s1"><messageEventDefinition messageRef="msgOrder"/></startEvent>
<startEvent id="s2"><messageEventDefinition messageRef="msgCancel"/></startEvent>

Defensive patterns

Strategy: validation

Validate before calling

Set<String> names = new HashSet<>();
for (String msgStart : collectMessageStartEventNames(processXml)) {
    if (!names.add(msgStart)) throw new IllegalStateException("Duplicate message start name: " + msgStart);
}

Try / catch

try {
    repositoryService.createDeployment().addClasspathResource(model).deploy();
} catch (org.activiti.engine.ActivitiException e) {
    if (e.getMessage().contains("multiple message event subscriptions")) {
        // fix the model: make each message start event name unique
    }
}

Prevention

Model each message start event with a distinct message element/name
Review merged process models for duplicated start events
Validate BPMN with a schema/designer check before deployment

When it happens

Trigger: deploy -> addMessageEventSubscriptions when two or more message start events within one process definition (same resource) reference the same message name.

Common situations: Copy-pasting a message start event in the BPMN designer and forgetting to change the message name; merging process models that each used the same message name.

Related errors

AI-assisted analysis of flowable/flowable-engine@d6d39ce1c6 (2026-09-11). Data as JSON: /api/errors/6554abc6e403bc22. Report an issue: GitHub.

Appendix: source

Thrown at modules/flowable5-engine/src/main/java/org/activiti/engine/impl/bpmn/deployer/BpmnDeployer.java:407

            }

        }
    }

    @SuppressWarnings("unchecked")
    protected void addMessageEventSubscriptions(ProcessDefinitionEntity processDefinition) {
        CommandContext commandContext = Context.getCommandContext();
        List<EventSubscriptionDeclaration> eventDefinitions = (List<EventSubscriptionDeclaration>) processDefinition.getProperty(BpmnParse.PROPERTYNAME_EVENT_SUBSCRIPTION_DECLARATION);
        if (eventDefinitions != null) {

            Set<String> messageNames = new HashSet<>();
            for (EventSubscriptionDeclaration eventDefinition : eventDefinitions) {
                if ("message".equals(eventDefinition.getEventType()) && eventDefinition.isStartEvent()) {

                    if (!messageNames.contains(eventDefinition.getEventName())) {
                        messageNames.add(eventDefinition.getEventName());
                    } else {
                        throw new ActivitiException("Cannot deploy process definition '" + processDefinition.getResourceName()
                                + "': there multiple message event subscriptions for the message with name '" + eventDefinition.getEventName() + "'.");
                    }

                    // look for subscriptions for the same name in db:
                    List<EventSubscriptionEntity> subscriptionsForSameMessageName = commandContext.getEventSubscriptionEntityManager()
                            .findEventSubscriptionsByName(MessageEventHandler.EVENT_HANDLER_TYPE,
                                    eventDefinition.getEventName(), processDefinition.getTenantId());
                    // also look for subscriptions created in the session:
                    List<MessageEventSubscriptionEntity> cachedSubscriptions = commandContext
                            .getDbSqlSession()
                            .findInCache(MessageEventSubscriptionEntity.class);
                    for (MessageEventSubscriptionEntity cachedSubscription : cachedSubscriptions) {
                        if (eventDefinition.getEventName().equals(cachedSubscription.getEventName())
                                && !subscriptionsForSameMessageName.contains(cachedSubscription)) {
                            subscriptionsForSameMessageName.add(cachedSubscription);
                        }
                    }
                    // remove subscriptions deleted in the same command

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