View source for Modern UI is not accessible

=Modern UI is not accessible= 
<hr>
{{KB|{{WIP}}|{{ZCS 9.0}}||||}}

====Problem====
Modern UI is not accessible directly or its fall back to classic UI when clicking on Modern Web App.

====Solution====
Following are the possible solutions to fix this issue. 

=====Scenario 1=====
Try to reinstall "zimbra-timezone-data" package.

[RHEL/CentOS]
 yum reinstall zimbra-timezone-data -y 
 su - zimbra
 zmmailboxdctl restart

[Ubuntu]
 apt install --reinstall zimbra-timezone-data
 su - zimbra
 zmmailboxdctl restart

If ModernUI is still not loading then collect the browser debug logs (https://web_client_url/?dev=1) along with server logs and share with Zimbra Support for furtehr troubleshooting. 

# /opt/zimbra/log/mailbox.log 
# /opt/zimbra/log/zmmailboxd.out 
# latest install.log from /tmp/  [if available] 
# latest zmsetup.log (under /opt/zimbra/log)
# Output of "rpm -qa" or "dpkg -l" 

=====Scenario 2=====  

The value of an attribute ''zimbraFileUploadMaxSize'' can also cause this issue as Int cannot represent non 32-bit signed integer value "21474836480" while loading the modern UI.

Make the following changes :
 su - zimbra
 zmprov ms `zmhostname` zimbraFileUploadMaxSize 21474836480

Now access the Modern UI.

=====Scenario 3=====  

The partial upgrade can cause the issue. To verify it, check  /opt/zimbra/log/zmsetup.date-time.log and /opt/zimbra/.install_history files.


{{SubmittedBy|Krishna M. Bhosale}}

{{Article Footer|ZCS 9.0|2020-06-24}}