Thank you Vishnu, 
I know that, my question is for the "TypeError: not all arguments converted during string formatting"

Hello,

This is actually a warning message for Not enough inventory! . You may adding a product with on hand stock low than ordering qty.

Check Stock of the product while adding in sale order.

Hello Firas,

This is because of wrong string formatting passed when you try to raise warning.
Please use this:
('You plan to sell %s %s of %s but you only have %s %s available in %s warehouse.') % \
(str(self.product_uom_qty), self.product_uom.name, self.product_id.name, str(product.virtual_available), product.uom_id.name, self.order_id.warehouse_id.name)​ 

This will format into string.

Hope it helps!

Thanks,
Mayank Gosai