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SharePoint Online is a robust application that can handle a high volume of actions. Even when a SharePoint Online migration is going on, all users can use the resources and access their data. When the access requests reach a higher limit where all the resources are exhausted, such a situation is known as Throttling.

SharePoint follows the throttling facility as the technique to keep the ideal performance limit for all its services. Throttling limits the number of requests and user actions that run simultaneously to access the resources.

Experts claim there are rare chances of throttling in SharePoint Online as it provides more than 99% availability and accessibility for all the data. Most of the time, when the situation for Throttling occurs, it is due to the custom codes. Such codes are REST and CSOM, which consume the SharePoint Online resources.SharePoint Online resources

  1. The typical usage is always under the SharePoint limitation, and they never cause or experience Throttling.
  2. There are additional services that run routinely along with standard services. These further actions are OneDrive uploads, workflows, and customizations.
  3. The custom scripts that exceed the throttling limit are REST, CSOM and others. While an migration is going on and you are uploading to OneDrive, then you may feel that Microsoft OneDrive has stopped working.

How does SharePoint inform about Throttling?

As soon as the per-user resource usage crosses the throttling limit, SharePoint stops further requests for a shorter period.

  • Suppose the user tries to access site data or a document from a library in SharePoint Online. In that case, the browser will redirect you to a webpage informing you about the throttling details.
  • For the custom request calls, SharePoint will return an HTTP error (status code 429 or server too busy-503and).

If the Throttling continues to affect the migration process when you are trying to upgrade SharePoint 2016 to SharePoint 2019, SharePoint will completely stop all the ongoing operations. There will be no more requests and information in Microsoft’s Office 365 Message Center.

How to avoid Throttling issues in SharePoint?

Suppose you are running a migration from SharePoint on-premises to SharePoint Online or two tenants between SharePoint Online. In that case, there are some remedies to remove such Throttling problems.

  • Try to minimize the number of apps or operation requests from various users.
  • Reduce the call frequencies.
  • To manage your custom requests, use Microsoft Graph API rather than REST or CSOM.
  • Distribute your website traffic smartly so that a single process does not consume more significant resources.
  • Employ the Retry-After HTTP header.
  • Microsoft Graph APIs contain better scripting facilities and have the latest improvements. It also consumes lesser storage and processing power than other customer scripting services. Microsoft Graph APIs can reduce the chances of throttling substantially.
  • The Retry-After HTTP header is a valuable feature when you are facing Throttling. The header will ensure a minimum delay in resource requests while the throttling situation is resolved.
  • If you use the Retry-After HTTP header, SharePoint Online will automatically deduce the correct time to rerun the request. The unmonitored tasks continue to put requests aggressively and consume lots of storage and CPU power.
An automated SharePoint Migration Solution

The primary cause behind the throttling problem is an ongoing migration process where multiple other processes are still running. Microsoft experts also advise running migration at such a time when no other processes are running. There is no scheduling option while using the SharePoint Migration Tool (manual migration), and the migration process needs to be run instantly. The migration will fail during a throttling situation, and you have to restart it again. So, you can try Kernel Migrator for SharePoint.


The software interface provides all the necessary features to access SharePoint accounts (both on-premises and online). After applying the filters, you can create a scheduling job based on several parameters.
create a scheduling job based on several parameters

You can create the scheduling timing based on Daily, Weekly, Monthly, or Once Only options. You can choose a duration for each option with Start Date and End Date, and migration will run at a fixed time. A description window will show when the migration starts based on the selection.

Final Words

One cannot avoid Throttling in SharePoint. Instead, one can use the existing resources without breaking the Throttling limits. This is applicable for SharePoint migrations too.

If you want to achieve a smooth and successful migration, use Kernel Migrator for SharePoint software, and schedule the data transfer conveniently. Thus you can perform the migration within the Throttling limits.

Kernel Migrator for SharePoint