I’m also getting this can’t able to save change and create new one widgets
Hi there, @Nirali_G 
I am really sorry that you’ve encountered this issue!
I see that my colleague Irene has already contacted you in a support ticket. As she said, to find out what’s going on, we need you to take a screenshot of the Developer Console when you’re seeing the error on your screen.
This article explains how you can do that - How to take a screenshot of the Developer Console - Elfsight Help Center
Could you please share it with us?