None of the MS365 apps will open

Question

I have a new Macbook Air, M4, 16gb memory running Tahoe 26.3.1. I installed a brand new version of MS365 that has never been on this computer. I registered on your MS site which I also have never done before as I have always been Mac. I installed the desktop versions on this Mac. When I try to open any of the apps, I get an error saying that Microsoft Word (all the apps say the same thing) cannot be opened because of a problem. It says that all versions are up to date. Also, when I setup my profile on microsoft.com it did everything in Spanish instead of English which was another 20 minutes of wasted time. What is going on?

Answer 1

The behavior matches a known issue where Office for Mac apps fail to launch with a message like “Microsoft Word cannot be opened because of a problem” right after installation.

Use the following sequence on the Mac:

1. Completely remove the current Office apps and data
   1. Quit all Office apps.
   2. Open Finder > Applications.
   3. Use Command+click to select all Microsoft 365 for Mac apps (Word, Excel, PowerPoint, Outlook, OneNote).
   4. Ctrl+click the selected apps and choose Move to Trash.
   5. In Finder, on the menu bar select Go > Go to Folder…, enter: ~/Library/Containers/
   6. In Containers, move to Trash the folders that start with:
      • com.microsoft.Word
      • com.microsoft.Excel
      • com.microsoft.Powerpoint
      • com.microsoft.Outlook
      • com.microsoft.OneNote
   7. Go back to Library, open Group Containers, and move these (if present) to Trash:
      • UBF8T346G9.ms
      • UBF8T346G9.Office
   8. Empty the Trash.
2. Reinstall Microsoft 365 for Mac
   1. Sign in to the Microsoft account that holds the Microsoft 365 subscription at the services page: https://account.microsoft.com/services (from the context).
   2. Download the Office installer for Mac again.
   3. If the installer .pkg file does not launch from Downloads, move it to the Desktop and double‑click it there.
   4. If it still will not launch or shows an error, delete the .pkg, empty Trash, and re‑download using Safari as recommended.
3. If the installer or apps still will not run
   • Confirm that the Mac meets the current system requirements for Microsoft 365 for Mac as described in the system requirements documentation.
   • If the installer reports “unidentified developer” or “install failed,” follow the specific steps from the Office for Mac install/activate troubleshooting article (move the file to Desktop, Control‑click > Open, or re‑download in Safari).

After this clean removal and reinstall, launch Word from Applications. If it opens correctly, repeat for the other apps. If the same error persists after these steps, contact Microsoft Support directly from the Office for Mac install/activation help page referenced below so they can collect crash logs for this specific macOS Tahoe build.

The Spanish language issue on microsoft.com is independent of the Mac app launch problem. Once signed in to the Microsoft account portal, change the display language in the account/profile settings to English; this does not affect whether the Mac apps can launch.

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References:

• "Microsoft program cannot be opened because of a problem" error when you start an Office program
• What to try if you can't install or activate Office for Mac
• Download, install, or reinstall Microsoft 365 or Office 2024 on a PC or Mac
• Microsoft Office apps for Mac quit unexpectedly - Microsoft Q&A
• I have a subscription to Office 365 and want to install it on my new laptop - Microsoft Q&A