Microsoft Office Error 0x0 on Mac
Why It Broke on 13 July 2026 — and How to Fix It

1. What Actually Happened on 13 July 2026

Microsoft 365 and Office on Apple platforms don't just check a licence key — they check a digital certificate to confirm the licence is genuine. The certificate in use had a hard expiry stamped into it: 13 July 2026, 23:59:59 UTC. Microsoft issued a renewed certificate inside Office build 16.83 and later. Every build below that number is now holding an expired one.

That's the whole story. It isn't a hack, an outage, a billing problem or a macOS bug — and it's the reason the fix is usually just an update rather than anything dramatic.

What's affected: Word, Excel, PowerPoint, Outlook and OneNote — across Microsoft 365 for Mac, Office 2024 for Mac, Office 2021 for Mac and Office 2019 for Mac, on both personal and business subscriptions. Microsoft's own known-issues page for this was published within days and is now marked Resolved, with "update Office" as the official remedy.

Depending on your version you'll see one of two symptoms:

• Activation failure — the 0x0 error, a sign-in loop, or "we couldn't verify your subscription" even though it's active.
• Reduced functionality mode — the apps launch and you can read and print documents, but typing, formulas, editing slides and saving are greyed out. It's a viewer.

One more thing worth knowing if you use Office on an iPad or iPhone as well: the same certificate change applies there, and the equivalent requirement is iOS or iPadOS 17 or later with Office app version 2.93 or later. Updating the apps from the App Store handles it.

2. Start Here — Which Mac, Which Office?

Whether this is a two-minute fix or something that can't be fixed at all comes down to two numbers. Get them first — it saves you doing work that was never going to help.

1. Your macOS version

   Apple menu (top-left) › About This Mac. You want the name and number — for example macOS Sonoma 14.6 or macOS Monterey 12.7.

2. Your Office version and build

   Open Word (it'll open even if it won't activate) › the Word menu in the top bar › About Word. You'll see something like Version 16.78 or Version 16.9x. That number is what matters — not the year in the product name.

Now find your row:

* If About Word shows 16.83 or higher and Office still won't activate, the version isn't your problem any more — skip straight to Fix 2.

3. Fix 1 — Update Office (The Official Fix, About 2 Minutes)

This is Microsoft's own documented resolution, and for most people it's the end of the story. The only decision is where you got Office from, because the update lives in a different place depending on the answer. Getting this wrong is the most common reason someone concludes "updating didn't work".

If you installed Office from microsoft.com

1. Quit every Office app

   Word, Excel, PowerPoint, Outlook, OneNote — all closed. Outlook especially; it likes to keep running.

2. Open Microsoft AutoUpdate

   Finder › Applications › Microsoft AutoUpdate. If it isn't there, use Go › Go to Folder (⌘⇧G) and paste /Library/Application Support/Microsoft/MAU2.0/, then open Microsoft AutoUpdate.

3. Select Update All

   Let every listed update finish. On a slow connection this is the part that takes the time — the downloads are large.

4. Reopen Word and check

   Word menu › About Word should now show 16.83 or later. Sign in if prompted.

If you installed Office from the Mac App Store

1. Quit every Office app

   Same as above — all of them.

2. Open the App Store and go to Updates

   Choose Updates in the sidebar.

3. Update each Office app

   Word, Excel, PowerPoint, Outlook and OneNote individually if there's no single "Update All".

4. Relaunch and check

   Open Word, confirm it activates, and check the version in About Word.

Activated? You're done — nothing below this line applies to you. Still stuck on 0x0 with a build of 16.83 or later? Then the certificate isn't the problem any more, and there's a stale licence cached on the Mac. That's Fix 2.

4. Fix 2 — Clear the Cached Licence and Identity

Office keeps your licence and sign-in details in files on the Mac. When those files are stale — or when there's more than one licence in play — Office can keep reading the wrong one no matter how many times you update or sign in. Two ways to clear it, both far less destructive than a full wipe. Try them in this order.

Option A — Clear Application Data (from inside Office)

1. Open any Office app

   Word is fine, even if it won't activate.

2. Help menu › Clear Application Data

   It's in the top menu bar, not in Word's own preferences.

3. Tick Identities and License

   Then choose Clear.

4. Quit Office completely, reopen and sign in

   Use the Microsoft account your Office licence is attached to.

Option B — Microsoft's License Removal Tool

Microsoft publishes a small official installer that strips every Office licence file from the Mac. It's the cleaner way to do this than hunting down the licence file by hand.

1. Download it from Microsoft

   From Microsoft's support page "How to remove Office license files on a Mac". Take it from Microsoft directly — this is exactly the kind of tool that attracts fake download sites.

2. Run the .pkg and follow the prompts

   You'll need your Mac's admin password. Close the installer when it finishes.

3. Open an Office app and sign in

   Use the account tied to your Microsoft 365 subscription or your Office purchase. It should activate against a clean slate.

5. Fix 3 — Full Removal and Clean Reinstall

The last resort, and the one that does finally clear the stubborn cases. Set aside 30 to 45 minutes, most of which is the reinstall downloading. You'll need your Mac's admin password and your Microsoft account sign-in.

1. Quit every Office app

   Including Outlook and Microsoft AutoUpdate. Check nothing Office-related is still running.

2. Remove the apps

   Finder › Applications › drag Word, Excel, PowerPoint, Outlook, OneNote and Microsoft AutoUpdate to the Trash, then empty the Trash.

3. Make your Library folder visible

   It's hidden by default. Press ⌘⇧H to open your home folder, then ⌘J and tick Show Library Folder. Alternatively use Go › Go to Folder (⌘⇧G) and paste each path below.

4. Group Containers

   In ~/Library/Group Containers/ delete these three folders: UBF8T346G9.ms, UBF8T346G9.Office and UBF8T346G9.OfficeOsfWebHost. The middle one holds both the licence and your Outlook profile — see section 6.

5. Containers

   In ~/Library/Containers/ delete every folder whose name starts with com.microsoft. — except com.microsoft.OneDrive if you use OneDrive.

6. Application Support

   Delete ~/Library/Application Support/Microsoft if it's there.

7. Preferences

   In ~/Library/Preferences/ delete the files starting com.microsoft. — for example com.microsoft.Word.plist, com.microsoft.Outlook.plist, com.microsoft.office.plist, com.microsoft.autoupdate2.plist.

8. Caches

   In ~/Library/Caches/ delete the folders starting com.microsoft.

9. The system-level Library — the step most guides skip

   Open Macintosh HD › Library — the top-level one, not the Library inside your home folder. Remove any com.microsoft.* files from /Library/LaunchDaemons/ and /Library/LaunchAgents/, and delete /Library/Application Support/Microsoft (the AutoUpdate helper lives there). You'll be asked for your admin password.

10. Clear the Keychain entries

    Open Keychain Access (Applications › Utilities), search microsoft, and delete the Office, Outlook and ADAL entries. This clears cached credentials so you sign in fresh rather than re-using the broken session.

11. Tidy the Dock

    Ctrl-click any leftover Office icon › Options › Remove from Dock.

12. Empty the Trash, then restart the Mac

    Don't skip the restart. Those LaunchDaemons and LaunchAgents stay loaded in memory until you reboot, which is why a reinstall without restarting can land straight back on the same error.

13. Reinstall from wherever you bought it

    Bought from Microsoft: sign in to your Microsoft account and install from your account's services or subscriptions page. Bought through the Mac App Store: reinstall from the App Store. Installing from the wrong one is the most common reason a clean reinstall still won't activate.

14. Open Word and sign in

    Use the account your licence belongs to. It should activate.

6. Read This Before You Delete Anything

The cleanup in Fix 3 is safe for your documents — nothing in it touches your Documents folder, your Desktop or your files. There are exactly two things it can cost you, and both are avoidable.

7. When There Is No Fix

Two situations can't be fixed on the Mac you have, no matter how many reinstalls you do. We'd rather tell you that plainly than watch you spend a weekend on it.

Your Mac is on macOS 11 Big Sur or older

Office builds from 16.83 onward — the ones carrying the renewed certificate — require macOS 12 Monterey or later. On Big Sur, Catalina or anything earlier, there's no version of Office you can install that will activate. It isn't a fault and a reinstall won't change it. Your realistic options:

• Office on the web — sign in at office.com in Safari or Chrome. Free with a Microsoft account, and enough for most everyday Word and Excel work.
• Upgrade macOS — plenty of Macs from around 2015 onward can run macOS 12 or later. If yours can, this is the cheapest real fix, and it's a job we do remotely.
• Use a newer device for the documents that matter, and keep the old Mac for everything else.
• A free alternative like LibreOffice, which opens and saves Word and Excel files.
• Replace the Mac — worth pricing up if it's already struggling in other ways.

Tell us the model and year and we can say in a couple of minutes which of those actually applies to your machine.

You have Office 2019 for Mac

This one is worse, and it's worth being straight about it. Office 2019 for Mac's final build was 16.78, released in October 2023, and the product went out of support on 10 October 2023. Because it can't be updated to 16.83, its certificate can never be renewed. The apps still open, view and print — but creating, editing and saving are gone, permanently. There's no patch and no workaround.

The only route back to editing is a current version: a Microsoft 365 subscription, or a one-off Office 2024 licence if you'd rather not pay yearly. And to be clear about which versions this hits — Office 2021 for Mac is fine. It's supported until 13 October 2026 and updates past 16.83 normally.

8. Why "0x0" Tells You Nothing

0x0 is just hexadecimal for zero. It's the placeholder Office falls back on when something has failed and it has no specific code to report — the software equivalent of a shrug. It doesn't identify the licence, the certificate, your account or your version.

Which is why searching the code sends you down a rabbit hole of unrelated registry tweaks, disk-cleanup tools and Windows advice that has nothing to do with your Mac. Ignore the code. Route by the two numbers in section 2 — your macOS version and your Office build — and the problem becomes specific and solvable.

9. When to Call a Tech

Fix 1 handles most cases and needs no help from anyone. It's worth handing over when:

• Nobody knows which Microsoft account the licence sits on — sort this out before anything gets deleted.
• Outlook holds mail you can't lose — a POP account or "On My Computer" folders that need backing up before the cleanup.
• You've done Fix 1 and Fix 2 and it's still 0x0 — the full removal has a lot of steps and one missed folder puts you back where you started.
• You've got several Macs — a business is better off doing them in one pass and confirming every machine is past 16.83.
• You're on Big Sur or Office 2019 and want a straight answer on the cheapest way forward rather than a sales pitch.

This is a remote support job in nearly every case — we log in, you keep your Mac on your desk, and there's no waiting around for a visit. Remote support is $125/hr and onsite is $205/hr, and most 0x0 jobs are a single remote session where the bulk of the time is the installer running. If it turns into a version conversation instead, we'll tell you what your options cost before you commit to anything.

We look after homes and small businesses across Perth — Fremantle, Joondalup, Rockingham, Scarborough and Stirling included — and for this particular problem, most of them never need us at the door. If Office is part of a bigger business setup, our business IT support team handles Microsoft 365 across whole offices, and if the mail side is also playing up there's a separate guide to email setup and troubleshooting. Mac-specific problems beyond Office live with our Apple and Mac support team.