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How to Fix Excel Not Opening on Mac Due to Invalid Signature Error
Question details
The user is unable to open Microsoft Excel on a Mac due to an invalid signature or code-signing error, which prevents the application from launching.
- Product
- Microsoft Excel
- Device & OS
- macOS
- Scenario
- Attempting to launch Microsoft Excel on Mac after a macOS OS update or an interrupted Office update.
- Observed behavior
- Excel fails to open and macOS displays an invalid signature or code-signing error, indicating the system no longer trusts the application.
Ensure your Mac is connected to a stable internet connection and that you have your Apple ID or Microsoft account credentials handy, as you will need to reinstall the application.
Reinstall Microsoft Excel and Update macOS
A clean installation of Excel and updating macOS resolves most code-signing errors caused by corrupted or partial application updates.
Code-signing errors often occur when a macOS security update or a partial Office update breaks the application's trusted developer signature. Completely removing and reinstalling the app from a trusted source usually restores this trust.
Open Finder and navigate to the 'Applications' folder. Locate Microsoft Excel, right-click it, and select 'Move to Trash' (or drag the icon to the Trash).
Click the Apple menu in the top-left corner of your screen and select 'Restart' to clear out temporary system caches.
Once your Mac has restarted, download and install the latest version of Microsoft Excel directly from the Microsoft website or the Mac App Store.
Go to System Settings > General > Software Update and install any pending macOS updates to ensure full compatibility.
Approve Excel in System Settings
macOS might have actively blocked Excel from running due to strict Gatekeeper security settings.
Use WPS Office as a Reliable Alternative on Mac
If Microsoft Excel continues to fail to launch due to macOS security issues or code-signing errors, consider switching to WPS Office. It is a highly compatible, free, and lightweight alternative that runs seamlessly on macOS without complex licensing or frequent app-launch errors.
- 1. Download WPS Office: Visit the official WPS website and download the macOS installer.
- 2. Install the Application: Open the downloaded package and drag the WPS Office icon to your Applications folder.
- 3. Open Your Spreadsheets: Launch WPS Office and open your existing .xlsx files instantly without format compatibility issues.
Frequently Asked Questions
What does an 'invalid signature' error mean on Mac?
It means macOS's built-in security system (Gatekeeper) no longer trusts the application's developer certificate. This often happens if the app's files were modified, corrupted, or if an update did not complete successfully.
Will reinstalling Excel delete my saved spreadsheets?
No, moving the Microsoft Excel application to the Trash does not delete your saved .xlsx or .xls files. Your personal documents are stored separately in your user folders on your Mac.
How do I know if a macOS update caused the Excel error?
If Excel stopped opening immediately after you installed a macOS security patch or system update, the update likely altered system security protocols or invalidated the previous application signature. Reinstalling Excel typically resolves this.
What should I do if the Privacy & Security settings don't show a blocked app message?
If macOS hasn't explicitly blocked Excel in the settings, the issue is likely internal application corruption rather than a Gatekeeper block. Proceed with completely moving Excel to the Trash, restarting your Mac, and reinstalling the app.
