Pardon me for probably a very noob question, here. 
I was following a tutorial on Youtube. I got the project to work when I press run, and I exported it once. I was going to see if it would export again to see if I couldn't just add on to it, and now I get errors when I try. Unsure what is causing this.
What was the link for the tutorial?
Ugh, it has been a while... I "think" it was this one.
Is there a particular reason for using Godot 3.x ?
Developing for XR on 4.x should be more straightforward.
I used 3.x since... forever.
Sorry no experience in 3.x.
If you want your project to be future proof, you should go with 4.x: it uses OpenXR that is a widely adopted standard.
I thought 3.x had OpenXR as well. It doesn't?
You're right, there's XR plugin since 3.4.
