What does negative sellable on channel inventory mean?

Sometimes when stock is updated via OneCart to Lazada, you might see a failed response in the View Logs section. The error message looks like this:

{
  "code": "501",
  "type": "ISP",
  "detail": [
    {
      "code": "E0501",
      "field": "bizCheck",
      "item_id": 12345,
      "message": "negative sellable on channel inventory,entityId=123,id=456"
    }
  ],
  "message": "E501: Update product failed",
  "_trace_id_": "234234",
  "request_id": "121212",
  "shop_details": "Lazada: My Demo Shop"
}

What This Error Means

In simple terms, Lazada is rejecting the stock update because the new quantity you are trying to sync from OneCart is  lower than the number of units you have already reserved for a campaign  directly within Lazada’s Seller Center.

Lazada’s system sees this as a conflict: you cannot have, for example, 50 units reserved for a campaign if you are telling it your total sellable stock is only 30. The update is blocked to prevent you from overselling on a campaign you have already committed to.

Example Scenario

Let’s walk through how this happens with a product,  SKU ABC123 :

1. Initial State:  You have  100 units  of SKU ABC123 in your warehouse. OneCart correctly shows a quantity of 100, and this is synced to Lazada.

2. Campaign Allocation:  You log in to your  Lazada Seller Center  and create a “Mega Campaign”. You allocate  60 units  of SKU ABC123 to this campaign.

3. Stock Change:  A large order comes in from your Shopify store, or you do a stock take and find you only have  50 units  left in your warehouse.

4. OneCart Sync Attempt:  Your inventory in OneCart is updated to 50, and it attempts to push this new, lower quantity to all connected channels, including Lazada.

5. Lazada’s Rejection:  Lazada receives the update request for “50 units” but its internal logic checks against its campaign reservations. It sees a conflict:

As a result, your Lazada listing will continue to show the old, incorrect stock level, creating a risk of overselling.

How to Fix This Error

This error must be resolved within your Lazada Seller Center. You have two primary options:

1. Reduce the Campaign Allocation:

2. Remove the Product from the Campaign:

Once you have adjusted the campaign stock in Lazada, return to OneCart and  manually re-push the quantity  for the affected product. The update should now go through successfully.

Also, learn more about how OneCart SKU quantity works here: https://help.getonecart.com/help/why-is-onecart-quantity-less-than-my-warehouse-quantity