When copying to SharePoint Online with Content Matrix, the following errors appear in the migration logs:
1. The migration is paused because source server under load.
2. An error occurred during the operation of the service method. The request failed with HTTP status 429. 3.
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Best approach in this scenario is to create multiple connections to SharePoint Online using multiple user accounts, as MS throttling is user-account based.
Note this is just a recommendation, as there is no way for us to directly affect Microsoft-side throttling on SPO.
