1. Microsoft Outlook Won't Open On Mac 2018

Outlook has suddenly stopped working. Outlook 2011 for Mac application won’t launch or start. Splash screen comes up and then disappears again.Then the program quit.
Solution 1:- (Rebuild Outlook database)
Method 1: Press and hold Option key when launching Outlook to rebuild the identity.
Method 2: Press and hold Alt key (windows) and click the Outlook icon on on the Dock (If the icon not appears on dock, Go to /Applications/Microsoft Office 2011 folder and drag the outlook file to Dock).
Microsoft database utility will appear. Now click the Rebuild button.
It will reboot Outlook database. After it finished the process, click the Done button and close the Microsoft Database utility.
Method 3: Open Applications and choose Microsoft Office 2011 folder. Then select the office folder and find Microsoft Database Utility.app. Here you can find rebuild option.
Solution 2:- (Remove Outlook preference file)
Go to ~/Library/Preferences and delete Outlook preference file (file name starts with “com.microsoft”).
Solution 3: (Nano suggested)
Open Terminal app and type the following command to delete old preferences.

The Database Utility is located under Applications – Microsoft Office 2011 – Office – Microsoft Database Utility.app. I had to shut down my computer manually first, then refuse to enter a password for any application that sounded like it might be related to Microsoft so that Outlook would not open in the background and freeze up again and refuse to quit so the database could. To work around this issue, use one of the following methods: Select the Exchange folder in My Calendars. Open the calendar. Expand My Calendars to display the Exchange mailbox calendar, the On My Computer calendar, and calendars that are associated with any other accounts that are open in Outlook for Mac.; Select the Exchange check box. Why can't I see all my groups? I can't send or receive messages. I'm not receiving email or other items in my Exchange account. I can't connect to my Exchange account. Outlook for Mac crashes or runs slowly.

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Next type or paste the following command to kill the cached preferences.

Microsoft Outlook Won't Open On Mac 2018

Then launch Microsoft Outlook.
If the above methods doesn’t work, re-install office 2011 software.