When I use Elementor Pro then face the issue on WordPress Elementor Page panel builder backend. The Builder is not opening properly. So the question is:

How to fix Uncaught TypeError: t is null Error in Elementor Pro?

Click on Elementor >> Tools >> Version Control >> Change version 2.9.9 >> Click Reinstall  >> Save Changes.

https://docs.elementor.com/article/382-rolling-back-to-a-previous-version-of-elementor