Can't edit with Elementor

Hi! I am having problems for editing my site!! I desactivated all the plugins except: Elementor, GP and Woocommerce and it's impossible to do any changes in any pages. I try to edit with Elementor pages that exist and they charge but then can't do anything. When I try to open new pages Elementor shows error message.

If I try to edit with Worpress always show the same message "La respuesta no es una respuesta JSON válida"

I am absolutely lost in this point... :(

Thanks

Laura