Attachment Migration Skipped – TooManyRequests (4381374)

During Teams/Chat migration, the following error appears in the task logs:

Attachment migration skipped for message 'xxx'. Request failed with TooManyRequests status code ().
{"error":{"code":"activityLimitReached","message":"The request has been throttled","innerError":{"code":"throttledRequest","innerError":{"code":"quota"},"date":"xxx","request-id":"xxx",""}}}

This error is generated by Microsoft Graph API, not by On Demand Migration.
It indicates that the tenant has exceeded Microsoft throttling limits for Teams Chat/Attachment read operations.

• Migrating too many users/chats in a single task (e.g., 200+ objects).
• Running multiple migration tasks at the same time.
• Large Teams chats with many attachments.

Microsoft enforces these limits and temporarily blocks further requests until the rate limit window resets.

1. For chat migrations, avoid large batches.
2. Run only one chat migration task at a time
3. Allow the current task to continue. Do not stop the task unless it fully fails.
4. If the task fails completely, follow the guidelines in the On Demand Migration Best Practices document (.pdf):

https://support.quest.com/on-demand-migration/current/technical-documents