You are not allowed to modify the quantity of an inactive inventory item.

You can only sync to active items

Problem

You get an error that you cannot sync because the item is inactive.

Description

You marked some inventory as inactive and your orders still use that product.

Solution

Mark item as active

Here are the steps:

1. Log into QuickBooks.
2. Click the gear on the top right.
3. Click products and services.
4. Under the filter, select inactive:
   
5. Find the item that is inactive.
6. Mark it as active:
   
7. Resync your sales.