The URL seems to be different
If you have any (hardcoded) link that points directly to a userview page (e.g. https://samplejoget.com/jw/web/userview/leaveApp/leaveUV//applicationInquiry) that is working in Joget Workflow v5. The same link will no longer work in v6. This is due to the upgrade of Spring framework in Joget Workflow v6.
There is double forward slash in the link. We will need to add a (userview key) value in between them (e.g. _ )
The new working link would be https://samplejoget.com/jw/web/userview/leaveApp/leaveUV/_/applicationInquiry with an extra underscore in it.
Custom CSS
If you have written any CSS before based on v5, you will need to check again to ensure a consistent look and feel across when upgraded to v6.
Check for Missing Plugin