After update to 2.0: Warning: file_exists() [function.file-exists]

Today I updated WP to 3.6
NG wanted to be updated too. So I did.
After the update, one of my two galeries doesnt work anymore. I tried to recreate it, but the error gets back each time, no matter in which way or order I create it. (Import pictures from gallery, Upload pictures again, Use the ID from the working gallery, etc etc).

At first I got an error saying something about memory. Now this one is gone (dunno why and how). Instead I get this one:

Warning: file_exists() [function.file-exists]: open_basedir restriction in effect. File(/www/htdocs/w00e9b4f?page_id=1741&preview=true) is not within the allowed path(s): (/www/htdocs/w00e9b4f/:/tmp:/usr/bin:/www/htdocs/w00e9b4f:/bin:/usr/local/bin:/usr/share/php) in /www/htdocs/w00e9b4f/wp-content/plugins/nextgen-gallery/products/photocrati_nextgen/modules/wordpress_routing/adapter.wordpress_router.php on line 39

I get this error when I create a completely new gallery from scratch, or if I newly upload pictures, or if I use already uploaded ones, or if I use the ID of the working gallery.
The working gallery just works fine tho.

Right now the gallery doesnt show the error I mentioned above. Right now the link brings me to an empty page with the default background image?! I dunno whats going on here …

My website is:
https://www.vor-freude.com

The working gallery is here:
https://vorfreude-fotografie.de/galerie-familie/

The broken gallery is here:
https://vorfreude-fotografie.de/galerie-babybauch-und-baby/

I hope someone can send me feedback on this and that it is mistake I made which can be undone easily :-/

Regards from germany
Martin

https://www.ads-software.com/plugins/nextgen-gallery/