Don’t know if above is the best solution to this.
What happend is that meta_data isn’t stored as serialized data anymore, but as json encoded as base_64 in the meta_data DB field.
I found this solution to work:
open up nggScrollGallery.php
Go the part where the $pictures array is filled (from line 198).
Replace
$serialized_data = unserialize($picture->meta_data);
$aux["width"] = $serialized_data["width"];
$aux["height"] = $serialized_data["height"];
with:
$base64_data = json_decode(base64_decode($picture->meta_data), TRUE);
$aux["width"] = $base64_data["width"];
$aux["height"] = $base64_data["height"];
I have taken this code from an original function included with the next gallery plugin. So should be ok.
Don’t forget to rewrite all your metadata of the images (to make sure it is stored as json and decoded as base64).
good luck ??