front end editor not working in visual composer

I’m not able to use the front end editor in my wordpress visual composer. I purchased the symmetrio theme from themeforest. I’ve attached the error message. Can someone help me locate the issue?

Hello there,

This is a general forum and for the support, you should contact the theme author.
If you’re looking for a paid support, you can contact me via the email address given below:

gmail(at)moskvayigit.com

Best,

Yigit