OneNote files have ONE or ONETOC2 extension.
This article can help you troubleshoot 2 problems ONE or ONETOC2 files can cause during a migration.
Index
The OneNote Notebook contains files that will not be visible within the notebook
Symptoms
You migrate files into a OneNote folder and find this message in your migration report:
The OneNote Notebook '{0}' contains files that will not be visible within the notebook. Those files may only be visible from the explorer view at the destination.
Details
This warning message occurs when you migrate a file into a OneNote folder that is not associated with OneNote.
Since OneNote folders open the OneNote online editor, files not associated with OneNote are not visible in the notebook. You can only see or access the file using Explorer in ShareGate Migrate.
Solution
Migrate all your files except ONE and ONETOC2 out of the OneNote folder and into another folder within a document library that is visible to you.
Your folder becomes a OneNote file at the destination
Symptoms
When migrating a SharePoint folder that contains ONETOC2 files, the folder becomes a OneNote file at the destination.
Details
The destination SharePoint site interprets the source folder as a OneNote file at the destination because of the contained ONETOC2 files.
Solution
There are two possible solutions for this:
Solution 1
Delete the destination folders that appear as OneNote files.
Create the necessary folders at the destination.
Migrate your content to these folders.
Solution 2
In ShareGate Migrate, connect to your source and destination with Copy content only or one of the Import content copy features.
In the destination pane, right-click the previously migrated folders that appear as OneNote files to delete them (you can also delete them directly in SharePoint).
Click Option.
Select Filter options in the sidebar.
Under File extensions, select Exclude from the dropdown.
Type ONETOC2 in the field next to the dropdown.
Click the Save and close checkmark icon.
Migrate the folders you deleted at the destination in step (2).
Repeat steps (1) to (8) with these changes:
After step (3), change the operation mode to Don't copy existing items before proceeding to step (4).
At step (5), select Limit to from the dropdown to migrate the missing ONETOC2 files.