Error file_put_contents

If you're getting “error file_put_contents” when installing demo data, it means your server doesn't have writing permission. The demo install needs to upload and unzip files on your server, so you need to make sure wp-content folder is writable. 

Follow this guide to set the correct permission to your wp-content folder: http://www.wpbeginner.com/beginners-guide/how-to-fix-file-and-folder-permissions-error-in-wordpress/