Este posibil sa fie o problema de configurare. Incearca sa adaugi linia upload_tmp_dir=/tmp/ in php.ini (solutie gasita aici: https://wordpress.org/support/topic/...orary-folder-8)
sau
daca site-ul e facut cu Wordpress - define('WP_TEMP_DIR', dirname(__FILE__) . '/wp-content/temp/'); in wp-config.php (solutie gasita aici: uploads - Missing a temporary folder despite settings in wp-config.php - WordPress Development Stack Exchange)