Issue Summary
The documents: https://confluence.atlassian.com/adminjiraserver/use-a-cdn-with-atlassian-data-center-applications-974378840.html and https://confluence.atlassian.com/adminjiraserver/configure-your-cdn-for-jira-data-center-974378841.html do not mention known issue with CDN possibly misbehaving during ZDU upgrade (when cluster is in mixed mode). The recommended action is to disable CDN before the upgrade and enable it after the cluster is in stable state.
Steps to Reproduce
Navigate to https://confluence.atlassian.com/adminjiraserver/use-a-cdn-with-atlassian-data-center-applications-974378840.html or https://confluence.atlassian.com/adminjiraserver/configure-your-cdn-for-jira-data-center-974378841.html
Expected Results
We have instrustion in the document on what to do with CDN when performing ZDU.
Actual Results
No info.
Workaround
Currently there is no known workaround for this behavior. A workaround will be added here when available