Cannot sign-in. I believe I'm current on updates.

Craig Caughlan 20 Reputation points
2026-07-16T12:28:18.2466667+00:00

Mac OS Tahoe. I believe the MS app is updated as I went through an update procedure a couple of weeks ago.

I've changed my password a couple of times. Signing in with both password and email takes me to 0x0 error code. Trying to sign-in using SMS takes me to a page to confirm whether I'm a robot; after matching pictures and submitting, the page refusses to pass "Loading..." after five minutes.

I don't understand the Authenitcator app. I appear to be OK with it with security (face ID), but there's nothing there that says Open MS. I do not have the app on my iPhone.

I've restarted twice.

Please help; this has been a real time-waster. Thank you.

Microsoft 365 and Office | Subscription, account, billing | For business | MacOS
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Answer accepted by question author
Anonymous
2026-07-16T13:04:16.2666667+00:00

Hello @Craig Caughlan

I’m sorry you’ve had to spend so much time on this. There have been recent reports of similar 0x0 activation/sign-in errors on macOS, and in those cases updating the Office client and macOS version helped users activate again. To better understand the issue, could you please let me know:

  • Which type of subscription are you using (for example, Microsoft 365 Business Basic/Standard or Office 2019/2021/2024)?
  • What version of Microsoft Office is installed on your Mac? (Open any Office app > About Word/Excel)

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Following the changes introduced by Microsoft effective from July 13th, 2026, Microsoft 365 subscribers must use a supported version of Office for Mac. Versions prior to 16.83 are no longer supported for editing documents and may have activation or functionality issues. Additionally, newer versions of Microsoft 365 for Mac require macOS Monterey (version 12) or later.

You can find more details here: Update Microsoft 365 or Office on your macOS or iOS device | Microsoft Support

Since you are using macOS Tahoe, that is good to go. However, to be able edit, your Office app version must be higher than 16.83. You can download the newer version here https://learn.microsoft.com/officeupdates/update-history-office-for-mac#release-history-for-office-for-mac or try update the whole office application.

If you have Office 2019 for Mac, it reached end of support on October 10, 2023, and no longer receives updates. Because Office 2019 cannot be updated to the required version, this issue cannot be resolved by updating or reinstalling Office 2019 for Mac.

Could you please let me know your Office app version and the type of Microsoft 365 subscription you have? Once I have that information, we can continue troubleshooting the Authenticator issue and the sign-in error.

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  1. Craig Caughlan 20 Reputation points
    2026-07-16T13:56:44.87+00:00

    Thank you for your quick response.

    I've Microsoft Word for Mac - Version 16.65

    Mac OS Tahoe 26.5.2

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