Common Microsoft 365 Errors During Migration

This article addresses common errors encountered during Microsoft 365 migrations with CloudM Migrate, providing explanations and potential solutions.

Microsoft Throttling and Quotas

Microsoft 365 services, including Microsoft Graph (which CloudM Migrate utilizes), implement throttling and quotas to protect system resources and ensure service stability.

• Microsoft Graph API Limits:
  • Microsoft Graph generally limits requests to 2000 requests per second.
  • These limits are subject to change by Microsoft.
• Tenant Definition:
  • A 'tenant' refers to your Microsoft 365 organization where the application is installed. This can be the same tenant where your migration application was created (single-tenant) or a different one (multi-tenant).
• Layered Throttling:
  • Requests are evaluated against multiple limits simultaneously. These limits can vary based on factors such as:
    • Scope (e.g., per application across all tenants, per tenant for all applications, per application per tenant).
    • Request type (e.g., GET, POST, PATCH).
    • Other internal factors.
  • The first limit reached will trigger throttling behavior.

Example: ErrorQuotaExceeded

• Error Message:

  [2022-10-13 20:09:13.6813] [MailImporter] [Error] [6] [Test@cloudm.com] [] Unexpected exception processing import. Message is: “Destination: Exchange response error. Code: ‘ErrorInternalServerError’. Message: ‘An internal server error occurred. The operation failed.’. InnerErrorResponseCode: ‘ErrorQuotaExceeded’ InnerErrorMessageText: ‘Cannot save changes made to an item to store.’” cloud.solutions.Migration.ExchangeWS.ExchangeWSImporterException Destination: Exchange response error. Code: ‘ErrorInternalServerError’. Message: ‘An internal server error occurred. The operation failed.’. InnerErrorResponseCode: ‘ErrorQuotaExceeded’ InnerErrorMessageText: ‘Cannot save changes made to an item to store.’
  

• Cause: This specific error often indicates a mailbox folder limit has been reached. Exchange Online has a limitation of 1 million messages per folder.
• Resolution: (Further detail needed - e.g., advise users to reorganize mailboxes before migration, or note that this is a hard limit from Microsoft.)

Other Common Microsoft 365 Errors

Migration Failed: (401) Unauthorized

• Cause: This error typically indicates an issue with administrator permissions or credentials.
• Resolution:
  • Validate Admin Access: Ensure the administrative account used for the migration has full access rights over the users that are failing.
  • Check Credentials: Verify that the credentials entered into CloudM Migrate are correct and current.

403 Forbidden Auth Methods Error

• Cause: This error signals a problem with modern authentication or the Azure Application Registration used for the migration.
• Resolution Steps:
  1. Delete Existing App Registration:
     • Go to the Azure Portal: https://portal.azure.com
     • Navigate to 'App Registrations' and delete the existing application registration used for CloudM Migrate.
  2. Clear Office 365 Auth Tokens:
     • In CloudM Migrate, go to the 'Projects Page' and clear the Office 365 authentication tokens.
  3. Recreate App Registration (with PowerShell for MFA):
     • If Office 365 is the source and Multi-Factor Authentication (MFA) cannot be disabled, create a new Azure Application using the CreateAzureADApplication.ps1 PowerShell script.
  4. Enter New App Details:
     • Input the details of the newly created app registration into the appropriate source or destination settings within CloudM Migrate.
  5. Upload New Certificate:
     • Ensure the new certificate associated with the recreated app is uploaded to CloudM Migrate.
  6. Run Connection Test:
     • Perform a connection test in CloudM Migrate to verify the new configuration.

Migration Failed: Remote Server Returned (429) Too Many Requests

• Cause: The 429 error is a direct indication of Microsoft throttling. It means CloudM Migrate is sending too many requests too quickly, and Microsoft's systems are temporarily blocking further requests to protect their resources.
• Resolution:
  • Direct Resolution with Microsoft: There is no direct workaround within CloudM Migrate to bypass this throttling, as it's imposed by Microsoft. The only definitive way to lift this limit is to contact Microsoft Support and request a temporary throttling increase for your tenant.
  • Strategies to Mitigate Throttling (Delay):
    • Divide Migrations into Batches: Break down large migrations into smaller, distinct batches.