Thanks a lot. It solved my problem.
I have already a page that is live and includes elements that I have created. What I mean is that I can’t display the already existing page to modify it. The screen only shows me a blank page while I have already customized the homepage that is in production on my website.
As I have this issue after having updated my theme, is it possible to rollback to the backup of the previous version? If so, could you tell me how to do a rollback, save my customizations and then update again the theme and apply the customizations I have saved?