Ionic v3 project in Ionic v4

Ionic Framework ionic-v3
1

I have a project made with Ionic 3 (now I have ionic v 3.20).

If I upgrade Ionic to Ionic 4, my project will compile?

Thanks in advance.

2

Ionic CLI is not Ionic Framework.
If you upgrade your Ionic CLI from 3.20.0 to 4.x, your project itself will still be Ionic Framework 4 and work as before.