Hello,
You’re using old versions of the theme and Visual Composer plugin.
Please update them. Plugin can be downloaded at this link https://www.8theme.com/download-plugins/ .
Don’t forget to create a back up of your files and database before update!
https://www.youtube.com/watch?v=KdWESIIPU1k
Also update Revolution Slider plugin.
Thank you.
Regards,
Eva Kemp.