We just got an email, as below:
Greetings from Zoho Books.
We are enhancing the APIs and in that process, the node is_update_customer will be deprecated in the following APIs due to technical difficulties with the same:
....
The changes would be done next week and we suggest you to check and update the APIs you’re using (if any).
Seriously, you change the API and give your customer's only a 1 week notice? Is this how you want to treat your users?
Juergen