How to fix your site who updated 4.1 ( Visual Composer version) to the old 3.4 ( Page builder version)
Please follow the below steps.
1) Now you have updated the new visual composer version of spalab theme 4.1 to your old spalab version 3.4 or lower? So now the site is down with numerous errors? Or showing blank page? So please follow the next steps to fix your site.
2) Just download the fresh files from themeforest and you have 2 zip files. spalab-old.zip ( for old theme users) file and spalab.zip ( new visual composer version).
Theme folder structure
3) Just extract the spalab-old.zip file to folder named spalab.
4) Now just remove the theme files that you have uploaded in your server. If you have updated the designthemes-core-features plugin, just remove that plugin as well, if you have not updated the plugin then no need to delete it. Now just upload the files in the spalab folder that you have extracted in step3 to your server inside the wp-content/themes/ folder.
5) Now check your site and your site will be back up.