Problem/issue: You got following error message in your XTCommerce 3.x?:
1146 - Table 'yourdatabasename.personal_offers_by_customers_status_' doesn't exist
SELECT max(quantity) as qty FROM personal_offers_by_customers_status_ WHERE products_id='someid' AND quantity<='1'
Check in customer groups settings in backend what is your default customer group, it should be guests with ID=2.
In case you can only access the database search for “DEFAULT_CUSTOMERS_STATUS_ID” in table “configuration”, set the value to 2.