Error Code: 6000 - Business Validation Error: Make sure all your transactions have a VAT rate before you save. Customer address updated in QuickBooks.
Reason for Error Code: 6000
This usually happens when Webgility is unable to find the rates for the tax location in QuickBooks. You need to check the sales tax item in QuickBooks and the rates associated with the sales tax item.
Troubleshooting for Error Code: 6000
1). Navigate to Settings> Accounting> Sales Tax in Webgility Online.
2). Refresh the Sales Tax settings and then Save them.
3). Check the same Sales Tax item in QuickBooks to verify whether rates are associated with the Sales Tax item or not.
4). If you modified the Sales Tax item in QuickBooks to fix the sales tax rates, then download the QuickBooks data from Webgility. Go to Settings> Accounting> Products.
5). Click on the dropdown, then select “Download from Scratch," and then click on the little refresh icon to download the products from QuickBooks. Click on "Save" to save the product settings.
6). Save the Sales Tax settings.
Post the orders again to QuickBooks and see if they are getting posted or not. If not, then you need to further check with the Webgility Support team to fix the issue.