Add new apps in Jira gets hanged when I search for any app in it after upgrading Jira datacenter

[Rashmi]

Hi! I have upgraded my testjira from version V8.7 to version 8.20.10 , my UPM is on v5.1.5.. after upgradation when I search for any new app in jira its gets hanged on UI it looks like it is searching for result but then it never returns any result and  if i try to go back or search another thing I found it is hanged though I can switch to another tabs like system or goto manage app again that works.. I thought it may be issue of firewall but then I checked and found out it has full internet access with 80/443 ... Though the firewall is not opened for *.cloudfront.net. 

Can you suggest what can I do to resolve it?

I cannot find any such warnings in logs.. though my health check shows some warnings like-