First of all I spent hours searching all the topics about the WordPress 3.5 upgrade and my specific problem is not listed. Besides that I had multiple problems after the upgrade (not be able to upload media, disappearing buttons in the text editor) so I made sure it wasn't plugin related.
I deactivated and reactivated all of my plugins, switched to the default Twenty Twelve theme, disabled my functions.php file, cleared my .htaccess, flushed my cache and even manually replaced all the wordpress core files on my server.
But I still get these warnings on the Permalink Settings page:
Warning: is_writable() [function.is-writable]: open_basedir restriction in effect. File(/) is not within the allowed path(s): (/home/username/:/tmp:/var/tmp:/usr/local/lib/php/) in /home/username/domains/domain-a.com/public_html/blog/wp-admin/options-permalink.php on line 131
Warning: is_writable() [function.is-writable]: open_basedir restriction in effect. File(/) is not within the allowed path(s): (/home/username/:/tmp:/var/tmp:/usr/local/lib/php/) in /home/username/domains/domain-a.com/public_html/blog/wp-admin/includes/misc.php on line 133
Besides that, it says my .htaccess is not writable, even when I change the permissions to 777. My site is fully functional by the way, but I would like to find out where these warnings come from.
Because when I change the Site Address to domain-a.com, the warnings disappear.
The thing is, this worked perfectly from WordPress 3.2 to 3.4.2.
Is this a 3.5 bug?
Any ideas? Thanks!