Unable to edit documents attached to Onenote

Question

We have a user who has built up a collection of notes in Onenote over the years and has recently "upgraded" to the Onenote desktop app from the Onenote for Windows 10 app after a laptop replacement. Now all of the attached Word docs, emails etc cannot be edited from Onenote. Previously and email could be opened, edited and saved back into the notes but now it opens read only and if you try to "save as" we get the following error:

"This message cannot be modified. You may not have permission to modify the message. To save your changes, click the file tab and then click save as" basically going round in circles!

I know that the Windows 10 version stored a copy of the notebook in "Documents\Onenote notebooks" but now its just a link to the online version and a cached files folder.

Is there anything we can do to get the original functionality back?

Answer 1

Dear @Glen, Kris,

Welcome to Microsoft Q&A. 

Thank you for explaining the situation so clearly. From what you described, this isn’t a permissions problem. It’s actually caused by a difference in how OneNote for Windows 10 (UWP) and OneNote Desktop handle file attachments. The Windows 10 app kept real editable copies of attached files in a local OneNote folder on your computer, so when you opened a Word document or an attached email, you were modifying an actual local file and saving it straight back into the page.

The OneNote Desktop app works differently. Attachments are stored inside the OneNote notebook itself rather than as real files in a folder. When Word or Outlook opens one of those embedded files, it opens from a temporary cache, which is why the document appears read‑only and cannot be saved back to the notebook. This is expected behavior in the desktop version and not the same editing experience you had before.

For email attachments (.msg), this limitation is even stricter: Outlook can open the file, but it cannot write changes back into OneNote, so those always open read‑only from OneNote Desktop.

If your goal is to regain the old “open > edit > save back into OneNote” workflow, the only reliable approach now is to treat the attachment as a real file again:

1. Save the document or .msg file out of OneNote to a regular folder.
2. Store it in a SharePoint/OneDrive location where you have full edit rights.
3. Insert it into OneNote as a link rather than an embedded attachment.

This way, you’re editing the real file directly, and your changes save normally, similar to how OneNote for Windows 10 handled the attachment.

I hope this information helps point you in the right direction. If you run into any issues while trying the steps, or if something still doesn’t feel quite right, please don’t hesitate to reach out again. I’ll do my best to support you however I can.  

Looking forward to hearing back from you with any updates or additional details. 

Warm regards, 

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Answer 2

It sounds like the issue you are experiencing is related to how OneNote handles attachments and permissions in the desktop app compared to the OneNote for Windows 10 app. Here are some potential solutions to restore the original functionality:

1. Check Permissions: Ensure that the user has the necessary permissions to edit the attached documents. If the documents are stored in a location that requires specific permissions, they may open in read-only mode.
2. Open in the Correct Application: When opening attachments, make sure they are being opened in the correct application (e.g., Word for Word documents). Sometimes, the default application settings may lead to files opening in a read-only state.
3. Check for Protected View: If the documents are opening in Protected View, this may prevent editing. You can adjust the settings in Word to disable Protected View for files originating from the internet or other potentially unsafe locations.
4. Local Copy: If the attachments are linked to the online version, consider downloading them to a local drive, editing them, and then reattaching them to OneNote. This can sometimes bypass permission issues.
5. Sync Issues: Ensure that OneNote is fully synced. Sometimes, sync issues can lead to files being temporarily unavailable for editing.
6. Backup and Restore: If the original functionality is critical, consider restoring from a backup of the OneNote notebooks that were created in the previous version. This may help in retrieving the editable state of the documents.

If these steps do not resolve the issue, you may want to consult Microsoft Support for further assistance.

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References:

• SharePoint files open as read-only