One or more of the document libraries on the user or group’s OneDrive contains more than 20,000 OneNote items (4374614)

One or more of the document libraries on the user or group’s OneDrive contains more than 20,000 OneNote items

OneNote tabs migration fails if the team contains a large number of items (folders or files, some of which could be OneNote entities such as notebooks, sections or section groups) and the following error message is reported:

Request failed with Forbidden status code (Forbidden). { "error": { "code": "10026", "message": "One or more of the document libraries on the user or group’s OneDrive contains more than 20,000 OneNote items (notebooks, sections, section groups). Please try again later."....

3rd party (Microsoft) OneNote REST API limitation. OneNote API calls can fail when they are executed against SharePoint document libraries that contain a large number of items (items can be folders or files, some of which could be OneNote entities such as notebooks, sections or section groups).

WORKAROUND1:
Before proceeding with migration consider the following Microsoft recommendations to avoid the problem: https://docs.microsoft.com/en-us/archive/blogs/onenotedev/onenote-api-calls-fail-with-a-large-number-of-items-in-a-sharepoint-document-library

For this 20,000 item error, the workaround is bring the item count in the document folder to be below 20000.

WORKAROUND 2
Before proceeding with Teams migration use SharePoint migration to migrate the site collections for affected teams. Then retry Teams migration without migrating SharePoint content.