401 Unauthorized

Hello,

I’ve just install and activate the AMP plugin but I have this error :

Warning: fopen(http://www.mysite.com/wp-content/uploads/2016/04/ban.png): failed to open stream: HTTP request failed! HTTP/1.1 401 Unauthorized in /public_html/wp-content/plugins/amp/includes/lib/class-fastimage.php on line 31

Do I have to change permissions on all my content folders?

Thanks

https://ww.wp.xz.cn/plugins/amp/