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Unable to Open Outlook on Mac – What Could be the Reasons?

Published By Ashwani Tiwari
Tej Pratap Shukla
Approved By Tej Pratap Shukla
Published On February 28th, 2022
Reading Time 6 Minutes Reading

Summary: After reading this you won’t have to look any further as this post covers all the solutions you can use to fix the “unable to open Outlook on Mac” issue. There will be some manual as well as an expert-recommended solution to resolve the issue.

It is frustrating for users when they are having a very busy day and they suddenly see that they are unable to view their Outlook on their Mac system.

What can be the reason for this? This can happen because of problematic add-ins, damaged files, corrupted profiles or navigation pane issues.

For quickly helping users, let’s jump right into the methods to resolve this error.

How to Solve The “Unable to Open Outlook On Mac” Issue?

There are a ton of reasons for which this error could be showing and different methods to overcome them. Following are the solutions:

  1. Microsoft AutoUpdate
  2. Main File System is Case Sensitive
  3. Run Updated Outlook & Mac OS
  4. Disable Add-ins
  5. Check for Outlook Profile Corruption
  6. Running Commands

Method 1: Basic Solution: Microsoft AutoUpdate

Before moving forward with any options, use the AutoUpdate tool as a first step to resolving “unable to open Outlook on Mac” error. You can go through the following steps to get started:

  1. Open the Microsoft Office 365 program.
  2. Select the Help option from the drop-down menu.
  3. Then select the option to Check for Updates.

If you find that there are no updates for your Office 365 program, then you can jump to the next solution or go to the method that solves your type of problem from the above section.

Moving on to the next workaround!

Method 2: When the Main File System Is Case-sensitive “Unable to Open Outlook on Mac” Error Occurs

The file is called OsfCore.framework in this example. The Mac Outlook 2016 application package is looking for a file called osfcore. framework, but it can’t find it. This problem can be simply solved by renaming the file to the osfcore.framework.

Follow the instructions below to solve this issue:

  1. In the Finder window, go to the Application
  2. When you right-click on Microsoft Outlook, choose Show Package Contents from the context menu.
  3. Look for the framework file in the frameworks folder to fix the “unable to open Outlook on Mac” issue.
  4. By clicking the Return key, select the selected file and rename it to osfcore. framework.

Method 3: Ensure You Are Running the Updated Outlook and Mac OS

To upgrade the Mac OS version, follow the procedures below:

  • Go to System Preferences and select Software Update from the drop-down menu.

If you’re on Mac OS High Sierra or an earlier version, the procedure will be different. You must first access the App Store before updating your Mac OS version to overcome the “unable to open Outlook on Mac” error.

  • Let’s see how we can update Outlook on a Mac machine:
  1. Open the Microsoft application, then go to the Help menu and select Check for Updates option from there.

The AutoUpdate feature will now do a check for updates. If there are any pending updates, click the Update button to start the process.

  1. Updating Mac Outlook will result in improved speed, new features, and maybe the removal of error warnings.

In case this is not the root cause of the error, simply move to the next procedure.

Method 4: Disable Add-Ins Available in Outlook for Mac to Resolve “Unable to Open Outlook on Mac” Problem

It’s possible that some add-ons are the cause of Mac Outlook’s inability to open due to a problem.

In such instances, it is recommended that these plugins be disabled or removed before attempting to start the application.

You must also ensure that all of these plugins have been updated to the most recent version.

When Outlook 2016 for Mac creates a problem and does not open, several people attempted this method and found it to be effective. There are no error messages in the application, and it functions as it should.

Method 5: Check If Outlook Profile Is Corrupted & Resolve the “Unable to Open Outlook on Mac” Error by Fixing it

Check if there’s a problem with your configured profile and you’re still having issues with Mac Outlook.

To create a new profile, utilize the Outlook Profile Manager program. After that, start Microsoft Outlook and make this profile your default profile.

If it works without a hitch, it’s your previous profile that’s preventing Mac Outlook from opening owing to a problem.

It’s possible that your old profile is corrupted, and Mac Outlook is unable to access its contents.

This can result in major issues, and you the “unable to open Outlook on Mac” will remain a problem until the profile is corrected.

If your Mac Outlook database could not be rebuilt and still has corruption problems, you can use a professional tool like Mac Outlook Database Rebuild Utility to export all of your data in a usable format.

Download Now Purchase Now

Mac OS 10.15, 10.14, 10.13, and 10.8 are all supported by the software. It’s really simple to use, and it works with Outlook for Mac 2019, 2016, and 2011.

How to Use the Software for Resolving this Error?

You can follow the given steps to understand how to use the tool:

Step 1 – Run this tool and choose the Mac Outlook version you’re using to fix “unable to open Outlook on Mac” issue.

Step 2 – To export the database in a healthy format, select an output format from a list of ten alternatives.


Step 3 – You can also use the software’s Advanced Settings to apply filters and hit Change to choose your destination location.

Advance Filters

Step 4 – Once you’ve made all of the necessary changes, click the Export button.

check the destination path

The tool will make sure that the folder hierarchy remains the same and there are no changes made to the data integrity.

Also, the Date-filter from Advanced Settings is used to export only selective data files.

Method 6: Run Following Commands to Solve “Unable to Open Outlook on Mac

The instructions and methods shown below will enable you to stop the preview of encrypted emails, which may be causing Outlook to freeze.

Open Terminal App after closing Outlook for Mac.

  1. Press Enter after entering the command listed below.
  2. By default, com is written.
  3. DisablePreviewForSMIME 1 Microsoft.Outlook
  4. Then run the following command: cfprefsd killall
  5. Finally, close the Terminal application and restart your computer. After that, open Mac Outlook.

Final Verdict

Many users have been complaining about the error “Unable to open Outlook on Mac” which has become a huge issue.

This can happen because of any of the reasons listed above. All the methods that can be followed to resolve the issue have been discussed in this article in detail. Choose the one as per your requirements.


By Ashwani Tiwari

I am an Expert Technical Analyst, specialized in assisting users with complex technological challenges. Through my blogs and articles, I offer expert guidance to help tackle these technical issues effectively. My true passion lies in providing valuable insights and simplifying complicated technicalities, enhancing user understanding and confidence.