QuickBooks Online Issue: Error: You can’t create or modify a transaction with a date that comes before you started tracking quantity on hand

To resolve this issue you will need to select a transaction date that comes before the date you started tracking the quantity on hand of these inventory items. Here are the necessary steps to correct this issue: 

1. Navigate to the Products and Services List
2. Click Edit
3. Select Adjust starting value
4. Click 'Got it'
5. This will open the START screen.
6. Change the Adjustment date to a few days before the transaction
7. Set the initial quantity to 0.  
8. Click Save & Close.