Cannot open Outlook and Onedrive in Safari on Mac

Hi there, Christopher! This is Marc. Thanks for reaching out to the community.

I recommend first to double-check your Mac’s date, time, and time zone in System Settings > General > Date & Time, even a small mismatch can cause certificate errors. If that’s correct, try updating macOS, as outdated system certificates can trigger this warning. You can also test by disabling any content blockers or extensions in Safari under Settings > Extensions.

If the problem persists, resetting Safari’s settings or removing/re-adding the affected websites from Settings > Privacy > Manage Website Data may help. In rare cases, corrupt certificates in your Keychain can cause this, so opening Keychain Access and running Keychain First Aid (or deleting outdated Microsoft certificates) can resolve it.

Let me know how it goes.

Best regards,

Hi Christopher Dougherty (22766027),

Thank you for posting to Microsoft Q&A Forum.

Here is an additional paragraph from Marc Vernon to clarify the situation and what you can try:

Based on what you have described, here are a few possible reasons why Safari on your MacBook Air is showing the “This connection is not private” error for Outlook and OneDrive, even though other browsers and devices work fine:

Safari’s Strict Certificate Validation

• Safari is more strict about SSL certificates than some other browsers. If there is a mismatch or issue with the certificate (even temporarily), Safari may block the site.

Fix:

• Try visiting the site and clicking “Show Details” on the error page, then choose “Visit Website” if available. If not, proceed to the next steps.

Date & Time Settings

• Even if your date and time look correct, they might be off by a few seconds or not synced with Apple’s servers, which can cause certificate validation to fail.

Fix:

• Go to System Settings > General > Date & Time and make sure:
• “Set date and time automatically” is turned on
• The time zone is correct

Keychain or Certificate Issues

Safari relies on macOS’s Keychain to validate certificates. A corrupted or outdated certificate might cause this issue.

Fix:

• Open Keychain Access (search in Spotlight)
• Search for any certificates related to microsoft.com, outlook.com, or onedrive.com
• Delete any that are marked as not trusted or expired
• Restart Safari

Safari Extensions or Experimental Features

Sometimes Safari extensions or experimental features can interfere with secure connections.

Fix:

• Go to Safari > Settings > Extensions and disable all extensions temporarily
• Go to Safari > Settings > Advanced > Show Develop menu
• In the Develop menu, choose Experimental Features and reset to defaults

Network Configuration or VPN

Even though you switched to a hotspot, some system-level network settings or VPNs can still interfere.

Fix:

• Go to System Settings > Network > Advanced and reset your network settings
• Disable any VPN or proxy temporarily

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