If you ‘ve ever had a problem updating WordPress Core or plugins from your backend. You are more likely having file permission issue. This can be vary but the solution below works for me like a charm!

define('FS_METHOD', 'direct');

Change Directories to 775 Permissions – Do this from the web root directory

sudo find . -type d -exec chmod 775 {} \;

Change Files Permissions to 664 – Do this from the htdocs folder.

sudo find . -type f -exec chmod 664 {} \;

Thanks to Sean Sasso