Office Home & Business 2021 (Perpetual License) cannot activate anymore on macOS Catalina – Error 0x0 after successful authentication

Question

Office Home & Business 2021 (Perpetual License) cannot activate anymore on macOS Catalina – Error 0x0 after successful authentication

Christian Herbert Hildebrand 0

Hello,

I would like to report what appears to be an activation service problem rather than a local installation issue.

Environment

•	Product: Microsoft Office Home & Business 2021 for Mac (Perpetual License) 

•	Microsoft account: License is correctly associated with my account 

•	macOS: Catalina 10.15.8 (Build 19H2036) 

•	Office installation:

◦	Original installer: Microsoft_Office_16.62.22061100_BusinessPro_Installer.pkg 

◦	Updated to Office 16.66.22101101 (last version supporting Catalina)

Description

Word starts normally.

When activation begins, I enter the Microsoft account that owns the Office Home & Business 2021 license.

Authentication itself succeeds.

Initially Office requested an email one-time code.

After resetting OneAuth credentials using

defaults write com.microsoft.Word ResetOneAuthCreds -bool YES

the sign-in process changed and now correctly offers:

•	Password 

•	Email verification 

•	SMS verification

I tested both password authentication and email OTP.

Both methods authenticate successfully.

Immediately afterwards Word always displays

Unknown Error Error Code: 0x0

At the same time another Office window remains open saying

Activating Office...

with an endless spinning indicator.

The activation never completes.

Troubleshooting already completed

•	Complete Office removal 

•	Fresh installation from the original Office 2021 installer 

•	Update to Office 16.66 

•	Removed Office-related Keychain items 

•	Deleted OneAuth data 

•	Reset OneAuth credentials 

•	Fresh Microsoft sign-in 

•	Password authentication tested 

•	Email OTP authentication tested 

•	Verified that the Office license is present in my Microsoft account 

•	Verified URL handlers (ms-word) 

•	Verified that MicrosoftRegistrationDB is recreated correctly 

•	Registration database contains hundreds of initialized entries 

•	System logs indicate Microsoft OneAuth activity before activation fails

Important observation

Authentication is successful.

The failure occurs after authentication but before activation finishes.

This does not appear to be an authentication problem.

Additional observation

During the activation process Word briefly displays an internal Microsoft message saying:

"You've reached a page that isn't normally displayed. Microsoft will never ask you to copy or share this URL."

The message disappears after about half a second and is immediately followed by Error 0x0.

I managed to capture this screen because it only appears very briefly.

Question

Has anyone else experienced this since mid-July 2026?

Could Microsoft please verify whether there is currently an activation service issue affecting perpetual Office 2021 licenses on macOS Catalina?

This Office installation worked previously on this Mac.

I am not requesting extended support or new features.

I simply need to activate a legally purchased perpetual Office Home & Business 2021 license that is already associated with my Microsoft account.

Any information would be greatly appreciated.

Thank you.

If this is a known backend activation issue, I would appreciate if this thread could be forwarded to the Office Activation/Licensing Engineering team.

This issue has already been investigated extensively. I am posting here after completing a detailed technical analysis, not as an initial troubleshooting request.

Kate Gerrish 5 Reputation points

2026-07-21T12:10:28.98+00:00

I have experienced exactly the same problem. At the beginning of July I was able to create, edit and save Word documents created with my legitimate Office Home and Business 2021 on my iMac which has the latest updated version of Catalina. - Since I came back from holiday on 19th July I cannot create a new Word document or edit one but can open and read an existing Word document. I cannot upgrade from Catalina as my iMac is too old for ios updates but continues to work well.

I have a second purchased copy of Office Home and Business 2021 which is installed on my MacBook and running Sequoia 15.7.1. This continues to work fine. So is the problem that Office Home and Business 2021 will no longer run on Catalina

Can this problem with Catalina be solved? Please advise
Christian Herbert Hildebrand 0 Reputation points

2026-07-22T16:29:21.37+00:00
Hi Kate,

I have exactly the same issue with a genuine Office Home & Business 2021 perpetual license on macOS Catalina 10.15.8.

The problem appeared suddenly in July after Office requested activation again. Sign-in succeeds, but activation always ends with error 0x0.

I have already carried out extensive troubleshooting, including:

complete Office reinstallation,

testing different Office versions,

resetting OneAuth,

removing Office credentials from Keychain,

creating a completely new administrator account with a fresh user profile and fresh Keychain.

The result is always exactly the same: successful sign-in followed by activation error 0x0.

This strongly suggests that the issue is not caused by a damaged user profile or a local installation. It seems to affect Catalina users after a recent change in Microsoft's activation service.

Hopefully Microsoft will investigate this, as more users are now reporting the same behaviour.
Stefan Blom 351.3K Reputation points MVP Volunteer Moderator

2026-07-22T19:17:10.28+00:00

@Kate Gerrish

Microsoft has stopped supporting Office under macOS Catalina. macOS Monterey or newer is required. This is not going to change, I'm afraid. See my Answer in this thread, which includes two links to Microsoft documentation and also a link to an article by John Korchok, a Microsoft MVP who knows Office for Mac very well.

On the machine with Catalina, you have to use the web versions of Word, Excel and PowerPoint, or you can try an open source alternative to Microsoft Office.
Kate Gerrish 5 Reputation points

2026-07-22T19:48:32.3266667+00:00

Thanks Stefan - I now understand the problem and unfortunately there is no way to solve it with my current iMac which can’t go beyond Catalina because of its age. It is so frustrating because the iMac has a 27inch screen which is no longer available - and works well for my needs.

1 answer

Your answer

Kate Gerrish 5 Reputation points

2026-07-21T12:10:28.98+00:00

I have experienced exactly the same problem. At the beginning of July I was able to create, edit and save Word documents created with my legitimate Office Home and Business 2021 on my iMac which has the latest updated version of Catalina. - Since I came back from holiday on 19th July I cannot create a new Word document or edit one but can open and read an existing Word document. I cannot upgrade from Catalina as my iMac is too old for ios updates but continues to work well.

I have a second purchased copy of Office Home and Business 2021 which is installed on my MacBook and running Sequoia 15.7.1. This continues to work fine. So is the problem that Office Home and Business 2021 will no longer run on Catalina

Can this problem with Catalina be solved? Please advise
Christian Herbert Hildebrand 0 Reputation points

2026-07-22T16:29:21.37+00:00

Hi Kate,

I have exactly the same issue with a genuine Office Home & Business 2021 perpetual license on macOS Catalina 10.15.8.

The problem appeared suddenly in July after Office requested activation again. Sign-in succeeds, but activation always ends with error 0x0.

I have already carried out extensive troubleshooting, including:

complete Office reinstallation,

testing different Office versions,

resetting OneAuth,

removing Office credentials from Keychain,

creating a completely new administrator account with a fresh user profile and fresh Keychain.

The result is always exactly the same: successful sign-in followed by activation error 0x0.

This strongly suggests that the issue is not caused by a damaged user profile or a local installation. It seems to affect Catalina users after a recent change in Microsoft's activation service.

Hopefully Microsoft will investigate this, as more users are now reporting the same behaviour.
Stefan Blom 351.3K Reputation points MVP Volunteer Moderator

2026-07-22T19:17:10.28+00:00

@Kate Gerrish

Microsoft has stopped supporting Office under macOS Catalina. macOS Monterey or newer is required. This is not going to change, I'm afraid. See my Answer in this thread, which includes two links to Microsoft documentation and also a link to an article by John Korchok, a Microsoft MVP who knows Office for Mac very well.

On the machine with Catalina, you have to use the web versions of Word, Excel and PowerPoint, or you can try an open source alternative to Microsoft Office.
Kate Gerrish 5 Reputation points

2026-07-22T19:48:32.3266667+00:00

Thanks Stefan - I now understand the problem and unfortunately there is no way to solve it with my current iMac which can’t go beyond Catalina because of its age. It is so frustrating because the iMac has a 27inch screen which is no longer available - and works well for my needs.

Answer 1

Stefan Blom 351.3K MVP Volunteer Moderator

To run Microsoft Office, you'll need macOS Monterey or later. You also need an Office license which lets you install version 16.83 or later. See https://support.microsoft.com/en-us/office/lifecycle/officeinstall/update-m365-office-macos-ios.

You may also want to read the article at https://learn.microsoft.com/en-us/microsoft-365-apps/mac/certificate-update-mac-ios as well as https://www.brandwares.com/bestpractices/2023/03/most-recent-office-you-can-run-best-practices/ .

Christian Herbert Hildebrand 0 Reputation points

2026-07-19T13:09:36.5066667+00:00

Thank you for your reply. However, I believe there may be a misunderstanding regarding my configuration. I am not using Microsoft 365. I am using Microsoft Office Home & Business 2021 (Perpetual License), which has been associated with my Microsoft account since purchase. I am intentionally running Office version 16.66.22101101, which is the last version that supports macOS Catalina 10.15.8. This Office installation was previously activated and worked correctly on this Mac. My issue is not that I am trying to install or run a newer Office version.The problem is that a valid perpetual license can no longer be activated, even though authentication completes successfully (password or OTP both work). Immediately after successful authentication, Office displays Error 0x0 while the "Activating Office..." window continues indefinitely. For this reason, I believe this is an activation/licensing issue, rather than a compatibility issue. Could you please clarify whether activation of an existing Office Home & Business 2021 perpetual license on the last supported Office version (16.66) is still expected to work on macOS Catalina? Thank you.
Stefan Blom 351.3K Reputation points MVP Volunteer Moderator

2026-07-19T19:44:11.8866667+00:00

Read the linked articles carefully. The certificate update requires that you have a version of Office, either a perpetual license or a subscription, which is capable of running release 16.83 or later. It also means that you must have macOS Monterey or later.
Christian Herbert Hildebrand 0 Reputation points

2026-07-20T08:25:54.3133333+00:00

Thank you for the clarification and the links.

I understand the certificate update requirement. However, I still have one question:

My Office Home & Business 2021 license is genuine, associated with my Microsoft account, and Office 16.66 is the last version officially released for macOS Catalina.

Is Microsoft stating that an existing Office Home & Business 2021 perpetual license can no longer be reactivated on Office 16.66 running on macOS Catalina?

If so, could you please point me to the official Microsoft document that explicitly states this?
Stefan Blom 351.3K Reputation points MVP Volunteer Moderator

2026-07-20T18:52:53.39+00:00

Are you sure that your Office 2021 license won't let you install a slightly newer version? I haven't run Office 2021 on a Mac, so I have no personal experience of that setup.

Unfortunately, the issue here is that Microsoft has put a stop to older Office releases. I suppose there are potential security issues with letting people using outdated software, and both Microsoft and Apple limit usage for older versions. Just to be clear, I am not defending either of these big companies.

P.S.

The official documentation is in the articles I posted earlier:

https://support.microsoft.com/en-us/office/lifecycle/officeinstall/update-m365-office-macos-ios

https://learn.microsoft.com/en-us/microsoft-365-apps/mac/certificate-update-mac-ios
Christian Herbert Hildebrand 0 Reputation points

2026-07-21T08:29:49.9066667+00:00

Thank you for your honesty and for clarifying that.

I appreciate your time.

My remaining concern is simply whether Microsoft has intentionally disabled reactivation of existing Office Home & Business 2021 perpetual licenses on the last supported Office release for macOS Catalina, or whether this is an unintended activation issue.

I hope someone from Microsoft can clarify that point.
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Stefan Blom 351.3K Reputation points MVP Volunteer Moderator

2026-07-21T09:37:20.4566667+00:00

My remaining concern is simply whether Microsoft has intentionally disabled reactivation of existing Office Home & Business 2021 perpetual licenses on the last supported Office release for macOS Catalina, or whether this is an unintended activation issue.

I am not sure about the "rules" here. As far as I know, Office 2021 licenses shouldn't be affected, if you are able to upgrade to at least version 16.83. Unfortunately, I can't confirm this myself, because I do not have a version of Office 2021 installed. Another complication is that Office 2021 reaches end of support in October this year. You could try chat support at https://support.microsoft.com/contactus .

In addition, you can send feedback to Microsoft using the portal at https://feedbackportal.microsoft.com/feedback/ .