OneNote sync problem with error code : E0000644 9zu13 running MacOS

Kevin Fong 0 Reputation points
2026-03-13T00:56:42.4866667+00:00

My Onenote does not sync (only Saved offline) with error code E0000644 9zu13 on my MacBook Air running Sequoia 15.7.4. and my Onenote version is Version 16.107 (26030819) i.e. most updated version.

I'll appreciate any help on this!

Many thanks!

Microsoft 365 and Office | OneNote | For home | MacOS

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  1. AI answer

    2026-03-13T00:56:59.9333333+00:00

    Error code 0xE0000644 9zu13 in OneNote for Mac has been observed when section group or section names contain special characters that interfere with sync.

    To resolve this, follow these steps on the problematic notebook:

    1. Identify the specific section group where adding or syncing sections fails.
    2. Rename that section group to remove any special characters (for example, remove characters like "+", symbols, or other non-alphanumeric characters). Use only letters, numbers, spaces, hyphens, or underscores.
    3. Also rename any sections under that section group that contain special characters.
    4. After renaming, force a sync of the notebook:
      • On macOS, Control-click the notebook name in OneNote and choose the option to sync the notebook.
    5. Verify that new sections can now be added and that the notebook syncs without the 0xE0000644 9zu13 error.

    If sync issues persist beyond this specific error, also check the general OneNote sync guidance for Mac, including opening the notebook in OneNote for the web and closing/reopening it in OneNote for Mac, and verifying account authentication and updates.

    References:

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  2. Katerina-N 9,305 Reputation points Microsoft External Staff Moderator
    2026-04-12T22:08:20.43+00:00

    Hello Kevin Fong,

    This error E0000644 9zu13 is a OneNote sync issue. It’s usually related to notebook naming, sync cache, or a single notebook getting stuck. I suggest you try this:

    1. Check if the issue is the notebook or the Mac app

    Go to: https://www.microsoft.com/microsoft-365/onedrive/online-cloud-storage

    Sign in with the same account 

    Open your notebook in OneNote for the web

    Result:

    If everything looks correct > issue is with the Mac app

    If it doesn’t open or is missing content > issue is with the notebook itself

    1. Remove special characters (very common fix)

    This specific error is often caused by section/section group names.

    Look for names with symbols like: +, #, %, etc.

    Rename them using only:

    letters (A–Z)

    numbers (0–9) 

    simple spaces or - _ 

    Then try syncing again.

    1. Force sync manually

    Open OneNote

    Right-click (Control + click) the notebook

    Select “Sync This Notebook”

    1. Reset the notebook connection

    Before doing this, copy any important unsynced notes somewhere safe.

    Close the notebook in OneNote

    Reopen it from OneDrive (File > Open)

    1. If only one notebook is affected (workaround)

    This usually means the notebook is slightly corrupted.

    Create a new notebook

    Copy pages/sections into the new one (don’t move)

    Sync the new notebook

    Important notes:

     I hope this will help with your situation. Please feel free to reach back if you have further update or more questions.

    Best Regards,

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