Error Handling in Camunda

See how to catch the exceptions in Camunda with error catch events.

Prashanth Boorla

Aug. 06, 21 · Tutorial

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In this tutorial, we are going to learn about how to handle exceptions in Camunda. For this

Create a Spring Boot project with the embedded Camunda Engine using this link. Use version 7.15.0.

Other Requirements

Spring Boot 2.4.3
Camunda 7.15.0
Eclipse or any other IDE
Maven

Handle Exceptions in Camunda

Import the Maven project into Eclipse and add the required dependencies.

Create service task in Camunda modeler and add error catch event to that service task.
Whenever an exception occurred in the service task, an error catch event will catch the exception and throws that service task into the respective journey flow.
If you did not give any error catch event it will be created as an incident in the cockpit and the token will be rolled back to the start event.

Use Camunda modeler to save the below XML content with the .bpmn extension to get the process model, which is having an error catch event.

    Java
   
 

   <?xml version="1.0" encoding="UTF-8"?>
<bpmn:definitions xmlns:bpmn="http://www.omg.org/spec/BPMN/20100524/MODEL" xmlns:bpmndi="http://www.omg.org/spec/BPMN/20100524/DI" xmlns:dc="http://www.omg.org/spec/DD/20100524/DC" xmlns:camunda="http://camunda.org/schema/1.0/bpmn" xmlns:di="http://www.omg.org/spec/DD/20100524/DI" id="Definitions_12zbd5u" targetNamespace="http://bpmn.io/schema/bpmn" exporter="Camunda Modeler" exporterVersion="4.5.0">
  <bpmn:collaboration id="Collaboration_1vtn4s6">
    <bpmn:participant id="Participant_18yien5" name="Error Handling" processRef="Process_1jtu8ae" />
  </bpmn:collaboration>
  <bpmn:process id="Process_1jtu8ae" isExecutable="true">
    <bpmn:startEvent id="StartEvent_1">
      <bpmn:outgoing>Flow_0vs3b46</bpmn:outgoing>
    </bpmn:startEvent>
    <bpmn:endEvent id="Event_08wul9s">
      <bpmn:incoming>Flow_0kby2yc</bpmn:incoming>
    </bpmn:endEvent>
    <bpmn:sequenceFlow id="Flow_0vs3b46" sourceRef="StartEvent_1" targetRef="Activity_0snk7cd" />
    <bpmn:sequenceFlow id="Flow_0kby2yc" sourceRef="Activity_0snk7cd" targetRef="Event_08wul9s" />
    <bpmn:serviceTask id="Activity_0snk7cd" name="Service Task" camunda:delegateExpression="${ServiceTaskDelegate}">
      <bpmn:incoming>Flow_0vs3b46</bpmn:incoming>
      <bpmn:outgoing>Flow_0kby2yc</bpmn:outgoing>
    </bpmn:serviceTask>
    <bpmn:sequenceFlow id="Flow_0qbi7m4" sourceRef="Event_01bk0vq" targetRef="Event_0my2aab" />
    <bpmn:boundaryEvent id="Event_01bk0vq" attachedToRef="Activity_0snk7cd">
      <bpmn:outgoing>Flow_0qbi7m4</bpmn:outgoing>
      <bpmn:errorEventDefinition id="ErrorEventDefinition_1eepl13" errorRef="Error_00fdfpv" camunda:errorCodeVariable="code_variable" />
    </bpmn:boundaryEvent>
    <bpmn:endEvent id="Event_0my2aab">
      <bpmn:incoming>Flow_0qbi7m4</bpmn:incoming>
      <bpmn:errorEventDefinition id="ErrorEventDefinition_1hkclb7" errorRef="Error_00fdfpv" />
    </bpmn:endEvent>
  </bpmn:process>
  <bpmn:error id="Error_00fdfpv" name="BPMN_ERROR" errorCode="error_code" />
  <bpmndi:BPMNDiagram id="BPMNDiagram_1">
    <bpmndi:BPMNPlane id="BPMNPlane_1" bpmnElement="Collaboration_1vtn4s6">
      <bpmndi:BPMNShape id="Participant_18yien5_di" bpmnElement="Participant_18yien5" isHorizontal="true">
        <dc:Bounds x="129" y="52" width="600" height="316" />
      </bpmndi:BPMNShape>
      <bpmndi:BPMNEdge id="Flow_0qbi7m4_di" bpmnElement="Flow_0qbi7m4">
        <di:waypoint x="390" y="228" />
        <di:waypoint x="390" y="290" />
        <di:waypoint x="462" y="290" />
      </bpmndi:BPMNEdge>
      <bpmndi:BPMNEdge id="Flow_0kby2yc_di" bpmnElement="Flow_0kby2yc">
        <di:waypoint x="440" y="170" />
        <di:waypoint x="512" y="170" />
      </bpmndi:BPMNEdge>
      <bpmndi:BPMNEdge id="Flow_0vs3b46_di" bpmnElement="Flow_0vs3b46">
        <di:waypoint x="278" y="170" />
        <di:waypoint x="340" y="170" />
      </bpmndi:BPMNEdge>
      <bpmndi:BPMNShape id="_BPMNShape_StartEvent_2" bpmnElement="StartEvent_1">
        <dc:Bounds x="242" y="152" width="36" height="36" />
      </bpmndi:BPMNShape>
      <bpmndi:BPMNShape id="Event_08wul9s_di" bpmnElement="Event_08wul9s">
        <dc:Bounds x="512" y="152" width="36" height="36" />
      </bpmndi:BPMNShape>
      <bpmndi:BPMNShape id="Activity_0h53qgw_di" bpmnElement="Activity_0snk7cd">
        <dc:Bounds x="340" y="130" width="100" height="80" />
      </bpmndi:BPMNShape>
      <bpmndi:BPMNShape id="Event_1vjkbhx_di" bpmnElement="Event_0my2aab">
        <dc:Bounds x="462" y="272" width="36" height="36" />
      </bpmndi:BPMNShape>
      <bpmndi:BPMNShape id="Event_18eo0oc_di" bpmnElement="Event_01bk0vq">
        <dc:Bounds x="372" y="192" width="36" height="36" />
      </bpmndi:BPMNShape>
    </bpmndi:BPMNPlane>
  </bpmndi:BPMNDiagram>
</bpmn:definitions>

  

After copy-pasting the above XML file in the Camunda modeler you can see the below diagram.

Add the below snippet to the exception handling

Run the application using the main class file and observe the output where the exception is caught by the error catch event and passed through the error throws event.

Camunda

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Error Handling in Camunda

See how to catch the exceptions in Camunda with error catch events.

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Handle Exceptions in Camunda

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