Brief
Starting from 22 of September 2011 Google Merchant Center has enforced a number of new rules for product feeds submitted into their system. You can read more about the changes here:
http://www.google.com/support/merchants/bin/answer.py?answer=1346661
 
Solution
ViArt developers have prepared a patch to correspond to the new Google Base rules.
 
1. Please download this archive:
http://www.viart.com/downloads/google_merchant_center_update-4.0.8.zip
 
2. Extract the files to your shop in 'admin' and 'templates/admin' folders accordingly.
 
3. Once this is done, please update database by running the following script in your browser:
http://www.your_site_url/admin/google_base_db_upgrade.php
 
If you entered the link correctly you should see a message: "DB patched successfully".
 

Awesome! Thank you Vera & ViArt Team!

Attention! Google has added a new required parameter recently so you need download this updated patch:
http://www.viart.com/downloads/google_merchant_center_update-4.0.8.zip
 
And replace 'admin_export_google_base.php' in your 'admin' folder.
 
Regards,
ViArt Support

Thank

I am having an issue with this. I get this error:
 
No products to export
problem with access to folder
feed was not created
please check folder permissions
 
i am selecting to export filtered results, so i know there are products to export. I am also selecting my images folder, so the permissions should be fine.

Nevermind, found the fix on: http://www.viart.com/google_merchant_center_filtered_78.html