Error at login image upload and login page.

Hi,

This error appear in login image upload and the login page too.

"Warning: getimagesize(http://adbrand.com.br/wp-admin/images/wordpress-logo.svg): failed to open stream: HTTP request failed! HTTP/1.1 406 Not Acceptable in /home/adbrains/public_html/wp-content/plugins/ultimate-branding/ultimate-branding-files/modules/login-image.php on line 246"

Any idea what that can be?

Thanks.