403 Forbidden Access to this resource on the server is denied!

[stefy3xoxo]

I've recently installed coppermine on a new site, and everything looks fine, but if I go into the configuration menu, change something and then click save changes I keep on having this error in the galleryurl/admin.php:
"403
Forbidden
Access to this resource on the server is denied!"
But then if I go to the gallery the changes have been done.
How can I fix it?
And yes, I've changed the albums and include folders permissions to 777
Thank you!

[ron4mac]

As a general rule, you will get more help if you can provide a link to your gallery.

[stefy3xoxo]

The gallery is this one: http://www.dakotafanning.eu/gallery/

[ron4mac]

If I access your site as dakotafanning.eu and browse around a bit, the URL in my browser becomes www.dakotafanning.eu/... This could happen if you don't have the site URL entered appropriately in the config. Also, there could be an .htaccess file involved that may be causing your issue. And, finally, the Let's Encrypt certificate associated with your site is invalid (it's for s1.fanbulous.info).

[stefy3xoxo]

If I access your site as dakotafanning.eu and browse around a bit, the URL in my browser becomes www.dakotafanning.eu/... This could happen if you don't have the site URL entered appropriately in the config. Also, there could be an .htaccess file involved that may be causing your issue. And, finally, the Let's Encrypt certificate associated with your site is invalid (it's for s1.fanbulous.info).

How can fix it all? I imagine that for the Let's Encrypt certificate I should ask to my hoster, but for the other thing? Coppermine config seems fine.
Thank you so much