Problem Definition

Currently When moving Jira and Confluence to a cloud environment. The new environment has different URLs, which affects the confluence pages linked in Jira Custom Fields . 

Suggested Resolution

Confluence links in Jira custom fields need to be updated to match the cloud URLs

Temporary Resolution

In this case you contact Atlassian support by logging a request in support.atlassian.com and ask them to apply the workaround for this issue.

Team will try to follow a workaround under the boundaries of https://confluence.atlassian.com/confkb/after-a-successful-server-to-cloud-migration-url-links-are-broken-in-the-new-cloud-instance-1077781093.html to fix the problem.