The total items in a single folder exceed the 5,000-maximum threshold for SharePoint and OneDrive for Business migrations.
Note: We have removed this limitation. If you are still running into this error, please contact our Support team. See How do I get support for your products? for more information.
On-Premises SharePoint, SharePoint Online, OneDrive for Business, and MigrationWiz
Cause of error
Due to SharePoint and OneDrive for Business threshold limits, MigrationWiz cannot migrate a document library that contains a folder with more than 5,000 items (files and folders).
For more information: Read the Manage large lists and libraries in SharePoint article from Microsoft.
To resolve this error, divide the folder containing more than 5,000 items into separate subfolders that each contain less than 5,000 items. It may be necessary to view the OneDrive folder via a web page, and change the view to Tiles in order to see the number of items in the folder accurately.