Jira – How to automatically change the assignee when transitioning the workflow

Overview
This KB describes how to automatically change the Assignee when transitioning from one workflow step, or status, to another by using a transition. We’re going to add a workflow post-function onto that transition that will enable us to provide this functionality.

Workaround
Auto changing the assignee in each transition (Stage). In order to do that please follow these steps:

  1. Log in as a user with the JIRA application administrator global permission.
  2. Click the cog icon from the top bar and select JIRA Administration > Issues, then Workflows (in the left pane)
  3. Click View on the targeted workflow
  4. Click the name of the desired transition
  5. Enter the post-function tab
  6. Click Add Post Function
  7. Select Update Issue field
  8. Add
  9. Select Assignee in the Issue Field
  10. Start typing the user name in the Field Value text box or click the Select a User icon beside the text box and select the desired user and click Add.

https://confluence.atlassian.com/jirakb/how-to-automatically-change-the-assignee-when-transitioning-the-workflow-705954603.html