Update CLI to 4 ok?

I’m using Ionic 3. “ionic -v = 3.20.0”. I see there is a v4.2.1 for the CLI available now.
“The Ionic CLI has an update available (3.20.0 => 4.2.1)! Would you like to install it? (Y/n)”

If I do this update is it 100% transparent? or will I have to fix/change my code for my apps because it will break many different things?


My understanding is that the CLI version is different than the Framework version. I have updated my CLI to a version greater than 3.x and have not had any issues with a 3.x project.