2018.3 to 2019.x and vice versa

Hi
Considering trying the new 2019 Beta.
Not much info on upgrading projects from 2018.3 to 2019.x
https://docs.unity3d.com/2019.1/Documentation/Manual/UpgradeGuide20191.html

but I assume it will work.
But what about the reverse?
Once you open a project in 2019 I assume it will no longer open in 2018.3, or am I wrong?

 

just make a backup

 

downgrading is never officially supported.
it may work if none of your assets are reimported when you upgraded.

you should still make a backup / use version control

 

Assume simply deleting Project Library isn't enough...will make backup.

 

2019.x is not production ready. If you are working on a real project you want to release, you need to stick to 2018.x.