Is it a wrong config of my theme or local environment ?
I precise I’m .running my local env via a Docker setup with DDEV on WSL2, I’m normally respecting all needed config (PHP version…etc…). I installed Acorn via the plugin in Wordpress backoffice.
Any FSE/Gutenberg in that Sage theme? I encountered this error message, and in my case there was a theme.json and the required FSE templates in templates/, but remove_theme_support('block-templates'); was still used in the theme. This caused a contradictory state: FSE is enabled, but block templates feature is not.
Have you followed the recommendations in that thread?
Specifically, have you referenced this PR to make certain your theme is compatible with Acorn v3?