Stock error on checkout even thought there is enough stock

Replies: 0

I have a few items with low stock and no backorder.
If these are put in the cart, the checkout page gives an error that they are out of stock.

For example:
Bottle 1 (stock is 3), customer puts 3 in cart.
On cart page, nothing happens. But on checkout page it says that this item can not be bought because there is 0 stock.

When I change the stock to 4, and the customer tries to pay for 3, then it works. But putting stock back at 3, the same error happens.

Items that do have backorder possibility activated don’t give any problems.