Cannot open MS Word: notice says 'Microsoft Word cannot be opened because of a problem.'

The error "Microsoft Word cannot be opened because of a problem" on Mac is commonly caused when the Office app has been moved or duplicated. To fix it and then reinstall Microsoft 365 if needed, follow these steps:

1. Check the application path
   1. When the error appears, open Problem Details and System Configuration in the dialog.
   2. Note the Path shown for Microsoft Word.
   3. The correct paths for Office 2008/2011 are:
      • Macintosh HD\Applications\Microsoft Office 2008
      • Macintosh HD\Applications\Microsoft Office 2011
   4. If the path is different, move the Office folder back to Applications:
      • In Finder, locate the Office folder.
      • Select the folder.
      • On the Edit menu, select Copy Microsoft Office 2008 or Copy Microsoft Office 2011.
      • On the Go menu, select Applications.
      • On the Edit menu, select Paste Item.
      • Try opening Word again.
2. Remove duplicate Office/Word apps
   1. In Finder, select File > Find.
   2. In the search box, type Word (or Excel, etc.) and press Enter.
   3. Look for duplicate Office app icons.
   4. For any duplicates, select them, then File > Move to Trash.
   5. Empty the Trash.
   6. Try opening Word again.
3. Reinstall Microsoft 365 for Mac (re-download) If Word/Office still will not open, fully remove and reinstall Office for Mac:
   1. Quit all Office apps.
   2. Uninstall Office for Mac (remove the apps from Applications and related data as in the Q&A guidance).
   3. Sign in with the Microsoft account that owns the Microsoft 365 subscription at the services page (as described in the Q&A):
      • Go to the Services & subscriptions page at account.microsoft.com/services.
      • Confirm the Microsoft 365 or Office license is listed.
      • Use the Install option there to download the Office installer for Mac.
   4. If the downloaded Microsoft Office installer.pkg will not launch:
      • Wait until the download completes (around 1.5 GB).
      • Move the .pkg file from Downloads to the Desktop and double-click it.
      • If it still fails, delete the .pkg, empty Trash, then re-download using Safari from the Office sign-in site.

If the installer reports "unidentified developer" or "install failed," follow the additional steps in the installer troubleshooting article (upgrade macOS if required, re-download, and retry from Safari).

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
• I just bought Office for Home and Business and now "No license found" - Microsoft Q&A
• Microsoft Office apps for Mac quit unexpectedly - Microsoft Q&A