That looks like Zoho is not happy with the data you are sending, It might be worth sending the request to something like webhook.site so you can inspect the data and check that it matches what the API is expecting.
Ok sure, I am got getting error
But when the workflow or node is executed, it should generate a new access token so that i can pass it to another HTTP request node which is Invoice Create Http node
Currently i am not able to see the new access token which was suppose to generate after every scheduled execution
Have you followed the documentation for OAuth with zoho? I would have expected the parameters to be in the body not the query. It also looks like you don’t have a url query option for access_type=offline
That looks like your authentication is still not correct, have you verified that what you are doing in n8n is the same as what you are doing in Postman? It looks like you are getting the response back from Zoho so this will be an authentication issue.
Why are you using header auth as an option? Does the OAuth2 credential not cover what you need for this?