This error is thrown because Sage 50 Canada is not set to allow inventory levels below Zero.
If the integration creates a new Inventory Type item in Sage that does not already exist, the quantity on hand will default to 0. If this item is immediately applied to a receivable invoice, the integration will fail to create that invoice when this option is not enabled.
To enable this option, please go to Setup > Settings > Inventory & Services > Options and check to enable "Allow inventory levels to go below zero."
