You may use cURL, Postman REST Client or any other REST API client to perform the Update Issue PUT request. For all our Jira  Data Center / Server REST API go to Atlassian Developer REST APIs

最初のステップ

First, you need to identify the ID of the Epic Link custom field, which will be different across different Jira applications. Follow the steps below to get the ID:

• ⚙ > [課題] > [カスタム フィールド] に移動します。
• Search for "Epic Link"
• Click on ... > Configure next to the field
  
• Look at the URL and get the ID located at the end of it, as illustrated below:
  
  
  

Method 1 Using cURL

1. Send cURL command as follows:

   curl -v -u username:password -X PUT -H "Content-Type: application/json" --data @"/Users/admin/work/atlassian-support/workshops/epiclink.json" http://localhost:6310/j6310/rest/api/2/issue/10141

2. Example of JSON data (  Please make sure to replace XXXXX with the Custom Field ID identified in the preliminary steps):

   {
       "fields": {
          "customfield_XXXXX": "SSP-24"
          }
   }

Method 2 Using Postman REST client

Example (  Please make sure to replace the custom field ID in the payload with the Custom Field ID identified in the preliminary steps):