In OneCart, a SKU has their inventory deducted when an order comes in (as long as the listing is connected in OneCart, and order status is the same as your deduction settings).

So what happens when an order is cancelled? 

As a default, OneCart does not  put back (or increase) the inventory of the SKU in a cancelled order. The reason for this is that depending on the reason for cancellation, the seller may not want the SKU to be put back.

For example, if the order was cancelled because:

  1. The item was discovered as damaged in the warehouse before shipping
  2. The warehouse discovered they don't have the item
  3. The delivery company lost the item in transit

Or for other reasons where the actual item is no longer sellable, then the system would be wrong to "put back" the quantity in those cases.

For simplicity and to give sellers the maximum flexbility, OneCart does not put back the stock for cancelled orders. You will need to monitor and manage the inventory directly via your Cancelled Orders report:

However, please note that the specific ecommerce platform may put back the stock on the platform directly. So you can end up with an mis-match, where the stock might be 0 in OneCart, but actually 1 on the platform, because the platform has "put back" the inventory into the sellable quantity.