I can’t start Microsoft Outlook or receive the error “Cannot start Microsoft Office Outlook. Cannot open the Outlook Window”

Applies to: Outlook for Office 365, Outlook 2019, Outlook 2016, Office for business Outlook 2013, Outlook 2010.

Are you having trouble starting Outlook 2016, Outlook 2013, or Outlook 2010, or receiving “Cannot start Microsoft Outlook. Cannot open the Outlook window” error messages? We can solve the problem for you, or you can follow the troubleshooting steps we’re offering below to help fix these startup issues.

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We can diagnose and rectify multiple common Outlook issues for you. If our automated tool can’t fix your issue, or if you’d like to fix it yourself, see the next section.

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Start Outlook in Safe Mode and disable add-ins

Quite regularly, add-ins can interfere with Outlook. Opening Outlook in Safe Mode, which launches Outlook without add-ins loaded, can notify you if an add-in is the problem.

Note: If you permitted an ABBYY FineReader add-in, an obsolete version of the software may result in an Outlook startup error. For further details, see Office programmes may crash with the FineReader add-in installed.

Start Outlook in Safe Mode

  1. Select Start > Run.
  1. Enter Outlook /safe, and press OK.
  1. In the Choose Profiles dialogue box, confirm the default setting of Outlook and choose OK.
  1. If prompted, type your password and select Accept.


  • How do you know you’re working in Safe Mode? You’ll notice a label similar to the one below at the top of the screen.
  • The Outlook icon on your taskbar also informs you that the programme isn’t running normally.

If Outlook does open in Safe Mode, then the problem is likely to be one of your add-ins. You must cancel each of your add-ins before restarting Outlook.

Disable add-ins

  1. In the upper-left corner of Outlook, pick File > Options > Add-ins.
  1. At the bottom of the View and manage Office Add-ins, ensure the Manage box displays COM Add-ins, and then pick Go.
  1. As a precaution, when the COM Add-ins listing of your current add-ins opens, do one of the following:
    • Manually note the title of every selected add-in listed under Available Add-ins. or
    • Take a screenshot of the property sheet and save the picture to your preferred location.
  1. After you’ve collected the titles of the chosen add-ins, clear all selected check boxes, and then press OK.

Caution: Click a check box to clear it. Don’t choose an add-in and select Remove. If you have administrator rights, you could potentially delete the add-in. For this troubleshooting exercise, you want to disable, not delete, an add-in.

  1. Click File > Exit.


  1. Choose Start > Run, and in the Open box, type Outlook.

Note: If the programme loads correctly, it’s possible that one of your add-ins is the cause of the error and you must identify the relevant one. To ascertain which add-in is the problem, enable one add-in sequentially.

  1. In the upper-left corner of Outlook, press File > Options > Add-ins.
  1. Pick the check box adjacent to an add-in you want to re-enable, and then click OK.
  1. Repeat all steps until you’ve re-enabled all of the preset add-ins and highlighted the source of the error.

Important: Remember, if Outlook opens in safe mode, you’ve revealed the add-in you just enabled as a source of the error.

  • Restart Outlook again and disable the add-in you enabled that produced the problem, and then start Outlook.
  • Make sure you go through the restart-disable-restart process for every add-in that was originally enabled in Outlook. An error could be caused by more than one add-in.

Create a new Outlook profile

Your profile includes your Outlook settings. Occasionally, that profile can become corrupted. You can confirm if it’s corrupt by configuring a new profile and editing which profile is used when Outlook starts.

  1. To access the Control Panel, do one of the following:
  • For Windows Vista or Windows 7, select Start > Control Panel.
  • For Windows 8 and Windows 10, press Start, and then type Control Panel. Note: For Windows 10, in Control Panel, ensure the View by box in the upper-right corner is set to Category.
  1. Choose Mail.
  1. In the Mail Setup – Outlook dialogue box, select Show Profiles > Add.
  1. In the Profile Name box, enter the desired name for your new profile.

On the Auto Account Setup page for the Add Account Wizard, under E-mail Account, enter Your Name, E-mail Address, and Password, and then click Next.

Note: The Add Account Wizard automatically scans for your mail server settings.

  1. Press Finish and you’ll find the new profile name you added displayed on the General tab in the Mail dialogue box.
  1. Under When starting Microsoft Outlook, use this profile, pick Prompt for a profile to be used, and then click OK.

Use a different profile

  1. Restart Outlook.
  1. In the drop-down list in the Choose Profile dialogue box, press the new profile name you created.
  1. Click OK.

Should you decide to delete a profile, back up the data files first. All offline cached content will be erased when you select Remove. For more information, see Introduction to Outlook Data Files (.pst and .ost).

Note: If Outlook loads normally, then you’ve verified your Outlook profile as being corrupt and the root of your problem.

Repair your Outlook data files

Outlook holds all your e-mail messages, meetings and events, contacts, and tasks in data files. These files occasionally might become damaged. You can run the Inbox Repair Tool (scanpst.exe) to scan your Outlook data files and repair errors.

  1. Exit Outlook to use the Inbox Repair Tool.

Note: The content in the left pane is influenced by whichever Outlook version you’re using.

  1. Visit the links underneath for instructions according to your version of Outlook.

Run the /resetnavpane command

The navigation pane is the left farthest pane in Outlook where you’ll see your folder list and the icons to change between Mail, Calendar, People, and Tasks. Running the /resetnavpane command eliminates all customisations to the navigation pane.

  1. Quit Outlook.
  1. Select Start > Run.
  1. In the Open box, enter Outlook.exe /resetnavpane, and then click OK.

Check if Outlook is running in compatibility mode

Compatibility mode is designed to help a programme function on an older operating system. If Outlook is running in compatibility mode, you can disable that setting and determine if it solves the problem.

Note: This step only applies to Outlook 2013 or Outlook 2010. Outlook 2016 doesn’t have a Compatibility tab.

  1. Find the Outlook.exe file on your computer.
  • For Outlook 2013, you can locate this file in C:\Program Files\Microsoft Office\Office 15\ or C:\Program Files (x86)\Microsoft Office\Office 15\
  • For Outlook 2010, you can view this file in C:\Program Files\Microsoft Office\Office 14\ or C:\Program Files (x86)\Microsoft Office\Office 14\
  1. Right-click the Outlook.exe file, click Properties, and then press the Compatibility tab.
  1. If any of the boxes on the Compatibility tab are checked, uncheck them, then select Apply > OK.
  1. Reload Outlook.

This information was compiled using information courtesy of © Microsoft 2020. All rights reserved.

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