What is happening?
On June 1st, 2016 Intuit will discontinue all support for the QuickBooks Online v2 REST API. After June 1st, 2016 applications will no longer be allowed to make v2 API Calls.
Why is this happening?
About a year ago, Intuit announced the availability of v3 of the QuickBooks Online REST API. Since then, we’ve been encouraging you to migrate your apps from v2 to v3, in this post and this one. Today, Intuit is announcing an 18-month notice for the official discontinuation of QuickBooks Online v2 API. QuickBooks Online v3 provides the same functionality as v2 with improved usability and performance.
What are the next steps?
The developer relations team will be reaching out to you via email if you are still using the QuickBooks Online v2 API. Intuit will provide support for you and your team as you migrate from v2 to v3 via webinars, Google Hangouts, and email and forum support to discuss any and all questions you have about the change.
How do I get more help?
We will try our best to help you. Contact us @ http://developer.intuit.com/help
The Intuit Developer Group