passegua on "[Plugin: WP Super Cache] Cannot access wp-content/cache/1.html"

I try to verify cache, but I get the warning: "page not same, timestamp different or missing".

You should check Page 1 and Page 2 above for errors. Your local server configuration may not allow your website to access itself.

Indeed if I try to connect to:

http://lnx.sinapsi.org/wordpress/wp-content/cache/1.html

I get "500 Internal Server Error".

Moreover I activate the logging, but even the log txt is not accessible:

http://lnx.sinapsi.org/wordpress/wp-content/cache/156d41281362dd2bd36cb638391fec1a.txt

I get "500 Internal Server Error"

I tried to chmod 777 but the error is still there.

How solve it?

Thanks.

https://wordpress.org/plugins/wp-super-cache/