Error : Class 'Twig_Extension_Debug' not found

Hello everyone,

I developed my first website with grav, it's really a great tool.

My site is finished and works well locally, with Laragon. Now, I'm trying to put it online on my server butI get this error :

Error
Class 'Twig_Extension_Debug' not found

I also tried with an empty version of grav+admin from the official ZIP, without modifications, I have the same error.

Do I have to install or activate something on my server ? I have already contacted my hosting company but they doesn't know Grav and can't help me.

Thanks