Can't get Office 365 to run because of pre-existing Office 2016

Question

Can't get Office 365 to run because of pre-existing Office 2016

Walter Smith 10

I'm on a Windows 10 computer, which has Office 2016 installed, but I no longer have the activation key. I subscribed to Office 365 and installed it, but every time I try to open an Excel file, it looks like it starts to open in 365, but winds up opening in 2016, and then I can't edit the file. I've tried to uninstall Office 2016, but I don't see it on the list of apps available to uninstall. I tried the online repair of Office 365, but it didn't help. Any suggestions?

Keith Doolan 5 Reputation points

2026-03-21T15:31:10.8133333+00:00

Hi Walter,

You need to completely uninstall all office applications from your device as they can conflict.

Click this link Uninstall to run the office troubleshooter and follow the instructions.

When you're happy that all the applications have been uninstalled, reinstall Office 365.

Regards,

Keith Doolan

If you find the answer above helpful, please "Accept the answer" to help anyone in the community who might have a similar question to quickly find the solution.

Answer recommended by moderator

Walter Smith 10

I was able to fix this with the help of ChatGPT. The problem was that I had a previous institutional install of Office 2016. To fix:
Open an xlxs file

Choose file/account

Click "Switch License"

Sign in with the account tied to your Microsoft 365 subscription

Keith Doolan 5 Reputation points

2026-03-21T15:59:19.2066667+00:00

Excellent, that will work also. If you run into further problems, it's better to start on a clean slate.

Regards,
Keith

1 additional answer

Your answer

Keith Doolan 5 Reputation points

2026-03-21T15:31:10.8133333+00:00

Hi Walter,

You need to completely uninstall all office applications from your device as they can conflict.

Click this link Uninstall to run the office troubleshooter and follow the instructions.

When you're happy that all the applications have been uninstalled, reinstall Office 365.

Regards,

Keith Doolan

If you find the answer above helpful, please "Accept the answer" to help anyone in the community who might have a similar question to quickly find the solution.
Keith Doolan 5 Reputation points

2026-03-21T15:59:19.2066667+00:00

Excellent, that will work also. If you run into further problems, it's better to start on a clean slate.

Regards,
Keith

Answer 1

Stefan Blom 351.3K MVP Volunteer Moderator

The problem was that I had a previous institutional install of Office 2016. To fix: Open an xlxs file Choose file/account Click "Switch License"

It seems that you got it fixed, which is good news. :-)

If you are seeing both Office 2016 and Microsoft 365 listed in Installed Apps in Windows Settings, I would suggest that you uninstall the Office 2016 version. You may have to repair the remaining 365 install afterwards (see https://support.microsoft.com/en-us/office/repair-an-office-application-7821d4b6-7c1d-4205-aa0e-a6b40c5bb88b).

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