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Backup the “cache” folder under, you may have to enable hidden files: C:\\Users\\<username>\\AppData\\Local\\Packages\\Microsoft.Office.OneNote\_8wekyb3d8bbwe\\LocalState\\AppData\\Local\\OneNote\\16.0\\cache

Then reset OneNote from the Apps and Features dialog: Start > Settings > Apps > Apps & Features

Then re-open OneNote, and sign back in with your correct credentials.

Finally, close OneNote, copy the backed up cache folder from step one over the newly created cache folder, overwriting any existing files. Then open OneNote again and all of your items should synch almost immediately.

Source: reddit