You need to configure .htaccess so that it acts, or all the settings that it has, work for the entire site except one directory, or disable .htaccess in one directory.
Let's just say: everything that is written to the client in .htaccess , blocks what is needed for the admin.
PS I do not need to deny access to the directory or something like that, but exclude the folder from the actions of the overlying .htaccess .
Update
RewriteRule .* — [E=HTTP_IF_MODIFIED_SINCE:%{HTTP:If-Modified-Since}] RewriteRule .* — [E=HTTP_IF_NONE_MATCH:%{HTTP:If-None-Match}] It is necessary that the admin cache does not work.
Update
I tried to add Rewrite. Right?
RewriteCond %{HTTP_HOST} !^/admin/ [NC] RewriteRule .* — [E=HTTP_IF_MODIFIED_SINCE:%{HTTP:If-Modified-Since}] RewriteRule .* — [E=HTTP_IF_NONE_MATCH:%{HTTP:If-None-Match}]
^try to remove it, of course it will have to work for all admin folders, but I don’t think there are a lot of them - Mike