Using Postman CRM API Collection can't Generate Access Token and Refresh Token

Using Postman CRM API Collection can't Generate Access Token and Refresh Token

Hi,

I have been trying to explore the API using the Postman API Collection by following the instructions described here: https://www.zoho.com/crm/developer/docs/api/v2/api-collection.html

However, I have been unable to get step 4.2 to work "Generate Access and Refresh Tokens". I have been able to get past this authentication step using the Java SDK (com.zoho.crm:zohocrmsdk-2-0:3.0.0) so I think that all the parameters I provided are valid, but when I make that call in Postman I always get the "invalid_client" error.

I have checked the possible causes based on the "Possible errors" section of the following document but can't see the problem https://www.zoho.com/crm/developer/docs/api/v2/access-refresh.html :
  1. I am sure that client-id and client-secret parameters are set correctly in my Postman environment
  2. accounts-uri parameter is set to EU ( accounts.zoho.eu which seems to work via the Java SDK using EUDataCenter.PRODUCTION() )
  3. This is using a "Self Client" for which there is no option to select Multi DC. That should rule out the possibility of me having selected a different data centre.

Any suggestions what else I could be doing wrong?

Thanks