OneNote Sync Error (OneNote can't connect to the network. We'll try to sync your notes when the network is available. (Error code: 0xE000006B b6d09)

Yes, I did it the same here! I deleted the old notebook. Now, I have zero problems to sync. That is the definitely the solution to the problem. But is such a shame that Microsoft doesn't helped us in that way.

Thanks for your replies.

I switch the OneNote app to "OneNote for Windows 10".

It syncs perfectly fine, but I had to do the previous changes manually.

But the problem was to find this app in the Windows Store, it showed not up.

I had to share the link with another Windows Computer, which the app was already installed.

Maybe this solution works for others as well.

I also had to go into each device and close the notebook and add the new notebook. Then I went and deleted all the files for the old notebooks. This cleaned it up. FYI, this will not work with the One Note 2016 version of the desktop app.

Found a solution/workaround for when this happens. If you copy the notebook, close the old one, and reopen the new copy it will reset your sync. You may need to reshare the link with anyone else you want to work on the notebook. But this worked for me.

1. Open the Notebook that you want to copy.  With the Notebook open …
2. Click on "File" then "Export"
3. Export Current:  Click on "Notebook"
4. Select Format:  Click on "OneNote package (*.onepkg)"
5. Click on "Export" to begin the copy process
6. File Explorer opens---choose where the copy of the Notebook is to be placed (Ex. This PC, Documents folder or OneDrive, Documents folder).  Remember, if you want to be able to share this Notebook or access it from anywhere, it must be placed in OneDrive.  So, click on OneDrive, then Documents.
7. "Open" the Documents folder and give the Notebook a new name--it must be different from the original name of the Notebook, then click on "Save"
8. Open File Explorer again and find the Notebook with the new name.
9. Double-click on it to unpack it.
10. Click on "Create" to create the copied Notebook with the new name.
11. Good Luck

Dude! It worked very well here this! Since last week my OneNote wasn't syncing! I did this and worked well, but is funny because in the app says "not syncig", lol.

Found a solution/workaround for when this happens. If you copy the notebook, close the old one, and reopen the new copy it will reset your sync. You may need to reshare the link with anyone else you want to work on the notebook. But this worked for me.

1. Open the Notebook that you want to copy.  With the Notebook open …
2. Click on "File" then "Export"
3. Export Current:  Click on "Notebook"
4. Select Format:  Click on "OneNote package (*.onepkg)"
5. Click on "Export" to begin the copy process
6. File Explorer opens---choose where the copy of the Notebook is to be placed (Ex. This PC, Documents folder or OneDrive, Documents folder).  Remember, if you want to be able to share this Notebook or access it from anywhere, it must be placed in OneDrive.  So, click on OneDrive, then Documents.
7. "Open" the Documents folder and give the Notebook a new name--it must be different from the original name of the Notebook, then click on "Save"
8. Open File Explorer again and find the Notebook with the new name.
9. Double-click on it to unpack it.
10. Click on "Create" to create the copied Notebook with the new name.
11. Good Luck