We will perform our regular refresh of the API Sandbox database on December 22 at approximately 2pm US Pacific Time. Therefore, the Sandbox will be unavailable for a few hours.
As a result of this database refresh, all Sandbox user and account data will be erased. Therefore, you will need to first make a request without including a clientEmail header (call getClientAccounts for example) to create your five Sandbox client accounts.
-- Jon Diorio, Product Marketing
CORRECTION: Sandbox Maintenance is Dec 21
We apologize for the last minute change, but the Sandbox maintenance period will actually be conducted at 2pm US Pacific Time on Thursday, December 21 (and not Dec 22 as previously announced).