Hello @Sunil_1999,
It looks like @klaviyojad responded to a recent Community post where you were asking the same thing. If you didn’t get a chance to see their comment, I’ve included the post below:
Additionally, I think you may find it helpful to take a look at our How to Setup OAuth for Existing Magento 2 Integrations Help Center article if you haven’t already to ensure you’ve accurately updated your existing Magento 2 integration from API credential authentication to the new OAuth workflow.
You could also glean some potential solutions from the Community posts I’ve linked below which discuss a similar topic:
Since your issue also relates directly with your integration, you may also want to speak with your developer and see if there’s anything within your integration’s backend that could cause the oauth handshake to not succeed. You could also reach out to our wonderful Support colleagues who can potentially point you and your developer in the correct direction by identifying any blatant integration issues.
I hope this helps!
David