In some case if you are getting the error like this for example, then it means that your memory limit is lower than the requirement of the theme.
Fatal error: Allowed memory size of 94371840 bytes exhausted (tried to allocate 276717 bytes) in /home/dh_j2aq7v/dev1.rabbitclone.com/2017/ugodognet/wp-content/plugins/js_composer/include/classes/core/class-vc-base.php on line 812
Usually our theme needs a memory size of 256MB. If your memory size is low, please ask your hosting team to increase the memory size.
Also please check that your server has following limits as explained in our knowledge base link else contact your hosting support to do so.