I went through the process of getting an access token and a refresh token.  It was working for several days, but now I'm getting the following returned to me:

{"error":"invalid_code"}

When I try to make this call:

https://accounts.zoho.com/oauth/v2/token?refresh_token=REDACTED&client_id=REDACTED&client_secret=REDACTED&redirect_uri= REDACTED&grant_type=refresh_token

I've redacted any sensitive information in the URL above.  I could probably just generate new tokens, but trying to automate clicking the "Accept" button would be a messier solution.  Is our system just going to periodically break like this or is there something we can do to prevent this from happening?