The following messagesĪre in the Mac system log at each launch attempt:ġ/22/15 10:16:14.459 AM Microsoft Outlook: objc: Class PKeyFormatter is implemented in both /Applications/Microsoft Outlook.app/Contents/Frameworks/amework/Versions/A/MicrosoftSetupUIGemini and /Applications/Microsoft Outlook.app/Contents/Frameworks/amework/Versions/A/MicrosoftSetupUI.
I updated to the latest version of Outlook for Mac for Office 365 today via automatic updates and since then whenever I launch Outlook it displays the splash screen for a second and then immediately closes without an error message.