Does Microsoft Office 365 install itself automatically over Office 2016/2019?

[German]Users of Microsoft Office 2016 or 2019 may be facing a very messy problem. A reader pointed out to me that on two of his systems, the Office 2019 installation had suddenly been replaced by Office 365. Doing a quick search, I found more cases. Microsoft seems to have set all the switches towards Office 365 subscription and there are numerous pitfalls where upgrading to Office 365 is imminent.

Office 2016/2019 versus Office 365

Microsoft Office 2016 and Office 2019 (and also Office 2021) are packages whose license is purchased once and is then valid indefinitely (so-called perpetual license). Microsoft Office 365, on the other hand, is Microsoft's subscription model, which has to be renewed annually. The aforementioned Office packages are available for installation from Microsoft via a click-to-run installer package. The Click-2-Run packages pull their own updates and do not receive them via Windows Update.

Office 365 installed itself over Office 2019

German blog reader Reinhold S. contacted me by email the other days and reported a very unpleasant observation under the subject Observation MS Office 365 automatically installs itself over Office 2019.

Hello Mr. Born,

first of all many thanks for your efforts to create and maintain the blog, really a very good help.

I check it every day.

I have a small company, run my own Windows 2019 server with Exchange, SQL, AD, fileserver in Hyper-V which is racked at a hoster in Münster/Germany.

The Windows 10 client PCs are running Office 2019; where we primarily use Outlook as we still have an EPR/CRM running on the SQL.

So far so good.

Now it happened to me for the 2nd time, first on my PC, last week on the PC of a co-worker, that instead of Office 2019 Office 365 is running there.

We have a license for it (as a waste product on the MAPS program), but not on our company domain / mail address.

Getting rid of the Office 365 again was really a lot of work, it had persistently nested.

I think it is an extreme impudence that MS just like that, on a PC with user without admin rights, Office 365 "installed" over Office 2019.

Maybe you describe this on the blog.

I have found nothing on the net about this.

Greetings

Reinhold S.

Based on the email signatures, I know that the reader is active in the field of software development. When I asked if it could be tied to an Office update, or perhaps the "you're ready to try Microsoft 365" button often offered on Microsoft sites was selected, the following response came back.

Unfortunately, I can't tell if it was due to an update.

The employee can update Office (and Windows 10) herself with her user account, and she does so regularly.

She is so extremely cautious, a "You are ready to test Microsoft 365" did not come with her, and also not with me at the beginning of the year. She wouldn't click on it either.

I don't have any log files, unfortunately I don't have time to investigate. I will be at the Embedded World fair next week ….

Getting rid of MS 365 was not so easy, I uninstalled everything from MS, Teams, OneDrive, Office 2019 and MS 365.

Then reinstalled Office 2019 and did updates, so far it's holding.

Sounds pretty plausible to me – in the context of the company – too. So I planned the German blog post Aktualisiert Microsoft Office 2016/2019 auf Office 365? primarily as a honeypot to find out if there are more affected. And I got more feedback about this issue as reader comments.

Further reports in the internet

While writing these lines I became a little bit more clever. Because I probably used the more appropriate search terms and immediately came across various references.

Office 365 trial installation causes trouble

It's a popular game, systems are shipped from vendors with a trial subscription for Microsoft Office 365, which then causes trouble. I came across this Microsoft Answers forum post from 2019 while searching, which at least reports calamities.

Office 365 overriding Word 2019?

I have a new computer which came with a trial version of Office 365. However I have installed Word 2019, Excel 2019 etc. When I open a file it asks me to activate Office 365 which I cancel and then I can open with Word 2019 etc. Is there a way that I can open files directly with Word 2019Offic or Excel 2019?

Here one might suspect that the previous installation of the Office 365 trial subscription messed up there and prompted the user for activation. There is a second Microsoft Answers forum post with a similar experience:

Office365 overwriting my licensed Office 2016

Reader,

I bought my HP notebook Laptop (Windows 10) in 2017 with Office365 for one year.
I have not extended the 1 year as I did not need the Office365. Now I want to install a licensed Office 2016.
After I have downloaded the Office 2016 packet, I can start, for example the Office Outlook, correctly but after a couple of minutes it changes to Office365. Informing me that I have no license for Office365, which I knew.

Question:
How can I stop Office365 to overwrite my licensed Office 2016?

Thank you, VikingHans (NL)

Again, a previously installed Microsoft Office 365 was the cause that a subsequently licensed Office 2016 was not recognized. Here, an Office Clean tool from Microsoft could help, which removes all installation remnants. I had written something about uninstallation problems a long time ago in the article Uninstall Office 365 and install Office 2016.

Email address of an Office 365 tenant

Where there is also trouble is the case where email addresses of an Office 365 tenant are used in a Microsoft Office 2016 or 2019. The third case that has come to my attention with such an error pattern is described in this Microsoft Answers forum post from March 2022.

m365 overwrites Office 2019

I've got a windows 10 domain computer that has Office 2019 installed and activated. We do not have any cloud services, M365 or whatnot. A user with a domain account, that also has local admin rights, logged into the machine. The user proceeded to open Word 2019 and logged into 'Office' with a different companies M365 account. That account has a M365 license assigned to it. Once that was done, Office 2019 was 'updated' to M365 Office. Now any user on that machine has M365, but it is unlicensed because they do not have an M365 subscription.

I say 'updated' because if I go to add/remove programs in the old school control panel, only Office 2019 Professional Plus is listed. If I go to Apps and Features under settings, Office 2019 is also listed. There is no other Office or M365 products listed. Neither a Quick Repair or Online Repair let the system revert back to Office 2019.

So, how do I get Office 2019 back?

Is there a GPO or something I can deploy to prevent this from happening again? I just set in Group policies "Upgrade

Office 2019 to Microsoft 365 Apps for enterprise" to Disabled, but I'm not sure that will resolve it.

This Microsoft Answers forum post from October 2022 describes the same effect – Office 2019 was over-ironed by Office 365 after trying to sync a calendar entry with an Office 365 email address provided to it by an organization. This Microsoft Q&A post outlines a similar issue:

Office 2019 "upgrading" to o365

I have a client who has an Office 365 account. If I install Office 2019 on his machine and set up the O365 account in Outlook, Office automatically upgrades to Office 365. Why is this happening, and is there any way to keep it from happening?

All it took was setting up a customer's Office 365 account email address in Outlook, and Office 2019 upgrades to Office 365. A Microsoft employee then asks some questions, but the thread petered out. Again, Office 365 would need to be uninstalled with an Office Clean tool according to this article from Microsoft.

The cases exemplify how flawed Microsoft's software solutions are in this regard. Buyers of a perpetual license of Office 2016 until 2021 will look old as soon as mixed environments with Office 365 exist in the organization and are used in any Office application. Or am I missing something here.

Is there a GPO to block upgrades?

This Microsoft Answers forum post mentions a GPO that could be used to prevent "upgrading to Office 365" from any Office 2016/2019 packages – but I didn't find anything concrete here in a brief search. The only thing that could fit halfway would be the entry blockversion in the registry key:

HKLM\oftware\policies\microsoft\office\16.0\common\officeupdate

as described in this post. However, I have found posts where even GPOs to block Office 365 updates somehow do not work. Perhaps a blog reader, with experience administering Office 2016/2019/2021 and Office 365 in corporate environments, can shed some light on that.

On Facebook there was a feedback that you can give the Setup.exe in the config.XML an option, so that 2016/2019 becomes an "Apps for Enterprise" – but in the above cases I have not yet come across a hint.

The current ADMX templates for Office may be found at Administrative Template files (ADMX/ADML) for Microsoft 365 Apps for enterprise/Office LTSC 2021/Office 2019/Office 2016 and the Office Customization Tool for Office 2016.

Intune can cause conflicts

German blog reader Friedl S. contacted me by e-mail and gave a completely different reason for such a "reinstallation" – but it should not apply in the above case. Here is his hint (thanks for that).

Hello Mr. Born,

I'll say "Intune"…

I had this similar before, father had given his son the PC with MS-Office 2016 and only local Windows accounts.

Son works at bank or similar that use INTUNE for "orchestration" and logged in (probably login teams/MS account):

Result was immediate uninstall 2016s, install 365 and teams etc etc.

Every re-install was undone – until I uninstalled Intunes as well.

So if an Office 2016/2019 is "converted" to Office 365, keep this scenario in mind as well.

So if an Office 2016/2019 is "converted" to Office 365, keep this scenario in mind as well.

Update changes description

There is one more very special effect – Microsoft updates Office 2016 – 20121 (C2R installations) via update in a way that the "naming of the update button" later shows Office 365. However, the package itself is still an Office 2016-2021. The change in naming, along with icons can lead to user confusion. I took up the case in the blog post Microsoft is upgrading parts of Office 2016/2019 to Office 365 …

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