Solution:
Problem:
The problem happening because of the Visual Composer Plugin.
Solution for The Problem: The problem can be solved by UN-installing the Visual Composer Plugin and install the latest version of the plugin.
The direct plugin update will not work sometimes, So try to install by removing the folder of the plugin from the WordPress and upload the latest version manually and do the update.
Try to update the plugin with the Ultimate Visual Composer Version 3.16.12. This will solve your problem.