HTTP 403 “Invalid checksum” with a paid Kite Connect app

Ashwath

Hello,

I created a paid Kite Connect app and tested the login using Python on Windows. The browser login completes and returns to my local redirect URL, but the token exchange fails with:

HTTP 403
{"status":"error","message":"Invalid checksum.","data","error_type":"TokenException"}

My script calculates the checksum using the documented formula: SHA-256 of the API key + request token + API secret. I entered the API key and secret from my paid app.

Could you please advise what I should check next?

I have not included any credentials or request token for security.