Updating field based on custom field value in other project when linked

[Lee Cash]

Hi, 

I'm trying to use a Automation for Jira branching rule for when two Jiras are linked together across different projects, checking for a value in the first project and then updating the second ticket with a different value accordingly. 

When I'm in the branch I can check that the custom field in the first project is X but I'm not sure how to then set the value of a different custom field in the second project. I think it would be easier if both projects shared the same custom field but they don't. 

This field is not in the usual list so I'm already looking into the Additional Fields section. 

Essentially: how do I update a custom field when two Jiras of different projects are linked together and the custom fields are not the same. 

Thanks in advance, 

Lee

[John Funk]

Hi Lee - Welcome to the Atlassian Community!

Can you share of screenshot of the rule? That would be most helpful.