EXCEPTION THROWN – not defined for ExtensibleObject

Since the Update to the actual version i got the mentioned error if i call the website the first time.
That error happens not always but it can occur at any URL.

you can watch the issue here:
http://www.caja-flamenco.eu

If i deactivate NGG everything is fine but i cant leave NGG deactivated because there are galleries managed by NGG

What to do?

Regards axel

https://wordpress.org/plugins/nextgen-gallery/