This error is in regards to the Quickbooks certificate that is granted during the initial Integration call. If you're receiving it, you may need to remove the certificate and re-grant it:
Before doing that, confirm the location of the company file hasn't changed. You can confirm this by pressing F2 on your keyboard in Quickbooks, and making sure the Location on the pop-up matches what's on the SyncTool company file:
If the file is the same, we may need to remove the Quickbooks Certificate and re-grant it.
Please see below how to remove the Quickbooks Certificate.
You'll need to be logged in as Admin and in Single-User mode and then go to:
Once you've removed the certificate, you just need to run a Sync and it will prompt the certificate again. Here are the steps for that:
Press the “Sync” Button on the SyncTool. With QuickBooks open, you should see the QuickBooks Application Certificate pop up. Select “Yes, always; allow access even if QuickBooks is not running” and press “Yes” on the second pop up that appears to verify you want to give access.
Select log in as "Admin" and press “Continue” on the QuickBooks Application Certificate.
On the Access Confirmation pop up that appears, choose “Done”
The SyncTool logs tab should display all of the lists exporting successfully in green now that you have connected the tool.