Update to new major version can lead to some setting not being saved and there is a chance you won't be able to go back to the previous version after saving changes of the interface because of breaking changes. So do it carefully and at your own risk.
It is safe to create a separate project for the new version and copy settings from the old project. We highly recommend this way so you will able to revert any time.
We are always trying to make version updates fully compatible so you don't need to make anything on your own, but there could a few that can't be done automatically.
You can check your current Jet Admin version in Project Settings
What should be done before update:
If you have never saved Menu items – apply any change and save menu customization
What should be done after update:
If you use any 3rd party integrations – run Sync operation inside resource settings
The following functionality is temporary unavailable in 2.x.x:
Adding/displaying Custom Fields (ex. FlexFields)
Adding Collection segments in Menu
Adding Custom Views (ex. FlexViews)
Adding Webhook tasks
The following features will be deprecated in the future and should be reconfigured differently
Dashboard page type (use Custom page instead)
Collection Segments (use Menu items grouping instead)