SharePoint online uses throttling at different levels to ensure reliability & meet performance requirements the SharePoint online service. Throttling is a means by which any over use of resources is disallowed by SharePoint whenever a script or code gets executes. As the infrastructure for the Office365 is maintained by Microsoft this becomes inevitable to ensure the availability of the platform. This throttling is done at a user level & these limits are not defined.
What really happens when you get throttled?
1. Any page that you hit in the browser you get redirected to the throttle error page under layouts named
2. Any requests that you send to SharePoint online through code fails and returns with a HTTP status code 429 which is too many requests.
3. If the user continues doing the operations further then the system will end up blocking the process completely with a 503 service unavailable error.
How do you decorate your traffic
2. Enterprise Application – NONISV|CompanyName|AppName/Version