Summary:

When user is editing the transition name, the error "common.forms.ajax.servererror" is thrown in the UI. Here is the screenshot for more information. 

Environment :

8.13

Diagnosis:

• When checking the har file, check the PUT endpoint that tries to make the modification of transition name:

  rest/workflowDesigner/latest/workflows/transitions

  • You should see that it always picks up sourceStepId as 1 and system checks for step with that particular ID in system for that workflow:
    

• When checking the Jira logs, you should see the java.lang.NullPointerException as mentioned below:

  Uncaught exception thrown by REST service: null
  java.lang.NullPointerException
  at com.atlassian.jira.workflow.edit.Workflow.isDuplicateStepTransitionName(Workflow.java:793)
  at com.atlassian.jira.workflow.edit.Workflow.isDuplicateTransitionName(Workflow.java:743)
  at com.atlassian.jira.workflow.edit.Workflow.isDuplicateTransitionName(Workflow.java:506)
  at com.atlassian.jira.workflow.edit.WorkflowTransitionsImpl.verifyTransitionCanBeUpdated(WorkflowTransitionsImpl.java:325)
  at com.atlassian.jira.workflow.edit.WorkflowTransitionsImpl.updateTransition(WorkflowTransitionsImpl.java:95)
  ... 3 filtered

Cause:

As the step with ID 1 is not found in the system, it fails with NullPointerException. 

Solution:

• Export the workflow as xml.
• Open it is up in text editor. 

• Check for tag  <initial-actions> in the XML.

• Notice what step ID is mentioned in 

  <unconditional-result old-status="null" status="open" step="10">

• When status is open(which is create step), API checks for step ID 1 as next step. 
• Take the back up of XML. Modify this step ID to 1 and also track corresponding <step> tag to modify its ID as well to step id="1"
• Delete the existing workflow and import the modified one.

• Here is an example of edit workflow for reference: 

  
  

  Example: How to locate it in workflow: