Feature was not activated.
See product documentation:
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Prerequisites and Requirements for Migrating OneNote Notebooks
In order to migrate OneNote Notebooks:
·On both the source and target, the Site Notebook feature must be activated.
NOTES:
-For SharePoint Online, the Site Notebook feature is activated by default.
-For SharePoint on premises, the Office Web Application Server must be deployed before the feature can be activated.
·The action must be a Full migrations (i.e. with Overwrite settings enabled).
NOTE: Incremental migrations are not supported.
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