How to restore locally saved Cache data from a Onenote Notebook if Notebook does not open anymore anywhere?

Question

In March 2025 I tried to close a Notebook and it had sync issues so I closed the Onenote app (a big mistake as it now shows). I tried opening or sharing said Notebook on the website and app Onenote and Onedrive and cannot open or share it either. It only shows on the “start page” but not under “my files” on the Onedrive website and it still shows under “All Notebooks” in the OneNote App. I really need the notes in that notebook for university so for the love of god can somebody please help me recover this notebook. I assume there was a synchronisation error and now the Notebook is not properly saved on Onedrive but I still have the locally saved Cache data of it. I tried viewing what’s left of the notebook with fileditor with the cache data but I would really appreciate it if somehow knew a more effective way to recover the notebook from those cache data. I do not have a window product and can therefore not use their tools to recover the data. Please I really need those notes!

Answer 1

Hi @Sarah, 

Thank you for contacting Microsoft Q&A. 

I’m really sorry you’re going through this. I noticed you mentioned that you still have access to the locally saved cache data. That’s a very important clue, and I’ve looked into possible ways to recover content from that cache, especially since you're not using a Windows device. 
There’s a helpful discussion on Microsoft Q&A that outlines how to recover data from the OneNote cache on macOS: onenote for Mac: Recovering Data from OneNoteOfflineCache_Files - Microsoft Q&A

If you're using a Mac, you can try on this: 

1. Turn off all internet connections or One note will start syncing before you can complete the recovery 
2. Delete/remove One note from Applications folder. 
3. Find: com.microsoft.onenote.mac (In Library containers folder) 
   1. Close everything on desktop 
   2. Click on Go in the menu bar 
   3. Hold down option key, now you should see library click on Library 
   4. Open Containers folder 
   5. com.microsoft.onenote.mac should be in there (on to step 4) 
4. Open Time Machine 
5. Go to date you know files were there. 
6. Highlight com.microsoft.onenote.com and select recover 
7. Choose replace the existing file 
8. Then go to applications folder for the same date in time machine and recover the Onenote app 
9. Open Onenote 
10. Your files will be there but you’re not safe yet! 
11. Make another Notebook call it backup or whatever you want 
12. Copy all other note books contents into the new notebook you just created 
13. Turn on your internet connection allowing one note to sync 
14. Now some of the original files may be gone from original locations but if you copied them into the new notebook = backup they will all be there and you can put them back to their rightful place. 

Please note: If you’ve created new notes since March 2025, restoring from Time Machine will revert OneNote to that earlier state. You may want to back up any recent notes separately before starting.

I truly hope this helps! 

If you need any further assistance or have additional questions, please don’t hesitate to reach out. I'm here to help. 

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