The solution from rapace81 might work for some, but have in mind that various errors could occur. Make sure you have a complete update in place.
Other thing to try before changing the control-stack.php, or even after if there occur consequent errors:
Checking php version and updating to 7.3 or 7.4.
This works for me and customers.
Do this in your hosting interface or ask for support.
Other possibility is to roll back your elementor version (find it under elementor options/tools; version control).