During the Pimcore update from older versions to the most recent 10.5 at this time I’ve got the following errpr:
Attempted to load class "Twig_Function" from the global namespace. Did you forget a "use" statement?
To fix it add the following use statement to your class:
use Twig\TwigFunction;
And replace all Twig_Function to TwigFunction in your php class file code.