Error: "Cannot access protected property ..."

Hi, following a tutorial for cake 3.7 … but actually working myself with 4.2.3, at the stage where I’m implementing a new theme (Gentelella-Master) I’m running into an error

“Cannot access protected property Cake\Http\ServerRequest::$webroot”

What type of problem is it and how can I prevent from it ?

Also, how would I may have found help on it myself ? I googled it and searched the community here but with no success yet.

maybe this could help:$webroot

So from 4.0.0 you have to use

Hey Dirk,
thanks, that helped.
Other question, how do I mark an answer as the solution ?

That’s a Stack Overflow thing, not a Discourse thing.