You recieved this error because your database or 'PRIMARY' filegroup is full. You need to free disk space by deleting unneeded files, dropping objects in the filegroup, purge transaction logs, or setting autogrowth on for existing files in the filegroup.'
To fix do the following:
Note: Before you do any of these steps make sure you have a full backup of your database!
1) Restore your site from backup just before you upgraded the cart to restore a working cart
Shrink your database - clears transaction log
2) Load sql mgmt studio
3) Right click on the database name.
4) Select Tasks -> Shrink -> Database
5) Then click OK
To increase space allocated to your database:
1) Right click your database and select Properties
2) Select 'Files' on the left
3) Select the '...' button after the Autogrowth column rows and change them both to 'Unrestricted Growth' under Maximum File Size.
4) Click Ok
5) Reset iis.
Also in dnn try clearing your event log from the admin menu