I think I what happened here, jrlparts.
When importing stocks in QuickBooks Online, you'll need to make sure the stock tracking feature is turned on. Note that this feature is available in QuickBooks Online Plus. If you don't have the Plus subscription, you'll have to upgrade your subscription.
After turning on the stock tracking feature, you can already import the stocks in QuickBooks Online. Here's a link for reference: Import products and services into QuickBooks Online.
Aside from that, you can also enter the stocks manually: Add stock products in QuickBooks Online.
If you're stuck in the same scenario, additional details of the error would be much appreciated. This would help us know what's causing the error and how to fix it.