If you are receive above message, follow below steps:
1. Edit your item against which this error is coming up
2. Check Default Tax Account,
a. if it is GST@40%, make sure you have also made IGST@40%
b. if it is IGST@28%, make sure you have also made GST@28%
Both GST and IGST tax account should be made for any new tax groups.
How to make Tax Group, here's detailed guide for your reference: https://bookkeeperapp.zendesk.com/hc/en-us/articles/360004395294