OneNote Gem Add-Ins

Question:

When I open an old OneNote partition today, I get the following error:
 

This section isn’t available yet.
It was added from another device. You ‘ll be able to use it when that device syncs.
Section was last modified at 14 Apr 2025 15:02

 
What to do?

Answer:

This happens when you move a section, copy a section, or rename a section in OneNote.
OneNote also gave a detailed modification time: 14 Apr 2025 15:02
 

Science:

In computer, Move a file = Copy the file + Delete the file.
When you move a file from one folder 1 to another folder 2, it will do it in 2 steps:

1. Copy the file to folder 2
2. Delete the file from folder 1

 
So, after you move a OneNote section, you can't shut it down until OneNote fully syncs it to OneDrive.com.
If OneNote doesn't sync it to OneDrive.com completely, and you've uninstalled OneNote.
That's where the above happens.
 

Solution:

If you don't have a manual additional backup of your OneNote notes to somewhere else.
This OneNote section is completely lost. There is no way.