SharePoint Migration Error 429: Throttling Resolution Guide
Understand and resolve the HTTP 429 "Too Many Requests" error during SharePoint and OneDrive migrations.
What Is Error 429?
The HTTP 429 error occurs during SharePoint or OneDrive migrations when you start too many users at the same time. The target system (Microsoft 365) forcibly closes connections due to its throttling policy.
Common Error Message
"The remote server returned an error: (429) Too Many Requests"
This error indicates Microsoft is actively limiting your migration requests to protect service stability.
Why Throttling Occurs
Microsoft implements throttling to ensure fair resource allocation across all tenants. When migration traffic exceeds acceptable thresholds, Microsoft's systems automatically reject additional connections.
Throttling Triggers
- Starting too many user migrations simultaneously
- High API call frequency to Microsoft services
- Large file transfers consuming excessive bandwidth
- Peak usage times when Microsoft services are under heavy load
How to Resolve
There are two primary strategies to resolve the 429 throttling error:
Option 1: Retry Later
Wait for the throttling window to reset, then restart your migrations. Typically, waiting 15-30 minutes allows the throttling to clear.
Option 2: Batch Users
Divide users into smaller batches (15-20 users per batch) and start them sequentially rather than all at once.
Recommended Approach
Batching is the preferred solution as it prevents the error from occurring in the first place and provides more predictable migration progress.
Batch Migration Strategy
Instead of launching all user migrations simultaneously, divide them into smaller groups:
Step-by-Step Batching Process
- 1 Identify your batch size
Start with batches of 15-20 users. This is within Microsoft's acceptable request limits.
- 2 Start the first batch
Select 15-20 users in Cloudiway and begin their migration.
- 3 Monitor progress
Allow the batch to complete or reach a stable state before starting the next.
- 4 Start subsequent batches
Continue with additional batches, spacing them appropriately.
Batch Migration Diagram
Shows user batches being processed sequentially to avoid throttling
Best Practices to Avoid Throttling
Microsoft services experience less load during nights and weekends.
Pre-stage data in smaller increments before the final cutover.
Watch for warning signs of approaching throttling limits.
Give the target system time to process each batch before starting the next.
Cloudiway Handles Throttling
Cloudiway's migration engine includes built-in retry logic for throttled requests. However, implementing batching strategies significantly reduces the occurrence of 429 errors and improves overall migration speed.