Error Failed to resize image (original, thumbnail)
I see you use security plugins. This problem comes from lots of restrictions and limitations on your website. Please make sure there is no "/wp-content/ hardening" process in your security plugins or in server.
Something doesn't allow to write/edit/create file in /wp-content/ folder of WordPress. I recommend to go through all settings of your security plugins and disable hard limitation regarding file writing and anything related to wp-content folder.
Could you please send WordPress Dashboard admin and FTP loin details? This is the only way we can check this server specific problems. Please send it to support[at]gvectors.com email address.