To reproduce this bug:
- Go to Control Panel -> Server Administration -> File Uploads
- Press Save
- Add somethere Shopping Portlet - and try to add item with some image
You will get exception "Incorrectr image extension"
it happens, because Server Admin portlet stored empty value into DB for shopping.image.extensions property.
In this case, Server Admin portlet continue to display default extensions, but shopping portlet used empty value stored in DB.