How to Fix: Cannot Start Outlook, Cannot Open Window

Infopackets Reader Leona H. writes:

" Dear Dennis,

I'm trying to upgrade from Outlook 2010 to Outlook 365 and I it takes a long time to start, stating that it 'cannot start outlook, cannot open window' or such. Actually, the full error message is: 'Cannot start Microsoft Office Outlook. Cannot open the Outlook Window. The set of folders cannot be opened. The attempt to logon to Microsoft Exchange has failed.' I don't understand how to get around this problem. I currently have Office 2010 and Office 365 installed. It only happens when I launch Outlook 365. Initially when I started Outlook 365, it wanted me to sign into another account with no option to sign into the account that I wanted. I managed to get past that and entered in the correct account, but I keep getting the 'cannot start outlook, cannot open window' error. Can you please help? "

My response:

I asked Leona if she wanted me to connect to her PC using my remote desktop support service in order to have a closer look, and she agreed.

Below I will discuss my findings.

How to Fix: Cannot Start Outlook, Cannot Open Window

Microsoft has a support page that explains how to fix the "Cannot start Microsoft Office Outlook. Cannot open the Outlook Window" issue - though the solutions suggested were not complete, were in the wrong order, and did not work for me. I've therefore decided to write my own solution.

The solutions below will work for Outlook 2007, 2010, 2013, 2016, 2019, and Outlook 365.

Option #1: Start Outlook in Safe Mode and Disable Plugins

To run Outlook in Safe Mode, you will need to use the "Run" dialogue.

To do so:

1. Right click on the task bar, then select "Task Manager" from the menu. Next, click "File" -> "Run new task", then type in "Outlook /safe" (no quotes), and click "OK".
    
2. The "Choose Profile" window will appear; select your user profile and click "OK".
    
3. If Outlook launches, it most likely means you have a problem with one of your plugins. You will need to disable your plugins to get around this problem. To do so: click "File" -> "Options" -> "Add-ins"; near the bottom of "View and manage Office Add-ins", ensure that the "Manage" box shows "COM Add-ins," and then choose "Go".
    
4. At this point you will want to write down all the COM Add-ins listings in case you want to add them back in again later. When that is completed, clear all the selected check boxes and then click "OK". This will remove all of your add-ins from Outlook.
    
5. Click "File" -> "Exit", then try and launch Outlook again.

If it still doesn't work, try the next option.

Option #2: Reset The Outlook Navigation Pane

If the Outlook navigation pane is corrupt, resetting it will get passed the "Cannot start Microsoft Office Outlook. Cannot open the Outlook Window." error message.

To do so:

1. Right click on the task bar, then select "Task Manager" from the menu.
    
2. Next, click "File" -> "Run new task", then type in "Outlook.exe /resetnavpane" (no quotes), and click OK.
    
3. Try and launch Outlook normally.

If it doesn't work, try Option #3 below.

Option #3: Use ScanPST to Repair your Outlook Data Files

If your Outlook .PST / .OST data files are corrupt, it can prevent Outlook from loading. You can use ScanPST to repair Outlook PST and OST files (data files).

To do so:

1. First, take note of where your .PST and .OST data files are located. You will need to know the location in order to use it with the ScanPST repair program. To find the locations of your .PST and .OST files, use the Mail app in Control Panel.
    
2. Next, locate ScanPST.exe in your Office folder as suggested below:
   
   For Outlook 2019 - C:\Program Files (x86)\Microsoft Office\root\Office16
   For Outlook 2016 - C:\Program Files (x86)\Microsoft Office\root\Office16
   For Outlook 2013 - C:\Program Files (x86)\Microsoft Office\Office15
   For Outlook 2010 - C:\Program Files (x86)\Microsoft Office\Office14
   For Outlook 2007 - C:\Program Files (x86)\Microsoft Office\Office12
    
3. Double click ScanPST.exe to launch it, then choose one of your Outlook .PST and .OST data files to scan (noted in Step #1 above).
    
4. Try and Launch Outlook again.

Caveats: I suggest you choose the option to make a backup of the original PST file in case the repair option ends up corrupting it further. Do not run the ScanPST on the same PST or OST file twice or it will overwrite your original backup with an already-repaired (and possibly further corrupted) PST / OST file.

When I tried to test Leona's PST files (about 7 of them), they all reported corruption. What's interesting about this is that after I tried to repair the files, I ran the ScanPST again and the repaired file still reported corruption. This would be incredibly unlikely, since her Outlook 2010 works fine with the same .PST files.

If repairing the .PST files don't work for you, try the Option #4 below.

Option #4: Create a New Outlook User Profile and Set it as Default

Another reason why Outlook will fail to load may be due to a corrupt Outlook user profile. You can potentially get around this by creating a new user profile, then set is as default.

To do so:

1. Click Start, then type in "control"; wait for "Control Panel" to appear in the list, then click it. At the top of the Control Panel, select "View" -> "Large icons".
    
2. Next, locate the "Mail" icon and double click it. The "Mail Setup" window will appear. Click "Show Profiles", then click "Add". Enter in your name and email address (even if you already have the same one listed), and let the wizard finish to completion. When it completes, you will be taken back to the same window where you just added the new profile. Make sure you select the new profile and set it as default. This page explains how to create a new Outlook user profiles visually.
    
3. Try and launch Outlook again.

If it doesn't work, try Option #5 below.

Option #5: Ensure Outlook isn't Running in Compatibility Mode

Compatibility Mode may prevent Outlook from launching properly, if it is set as default - though this would be rare. To check if this is the case, you will need to locate the Outlook.exe executable depending on which version of MS Office is installed on the machine.

To do so:

1. Locate the Outlook.exe, navigate to one of the following folders:
   
   For Outlook 2019 - C:\Program Files (x86)\Microsoft Office\root\Office16
   For Outlook 2016 - C:\Program Files (x86)\Microsoft Office\root\Office16
   For Outlook 2013 - C:\Program Files (x86)\Microsoft Office\Office15
   For Outlook 2010 - C:\Program Files (x86)\Microsoft Office\Office14
   For Outlook 2007 - C:\Program Files (x86)\Microsoft Office\Office12
    
2. Right click the Outlook.exe file in one of the above folders, select "Properties," then click the "Compatibility" tab.
    
3. If any of the boxes on the Compatibility tab are checked, uncheck them, then choose "Apply" -> "OK".
    
4. Try and launch Outlook again.

If that doesn't work, try the next option.

Option #6: Create a New Windows User Profile

Unfortunately, none of the above options fixed the "Cannot start Microsoft Office Outlook. Cannot open the Outlook Window" error for Leona.

The only solution that worked for me was to create a new user profile in Windows, then re-attach all of Leona's .PST and .OST files into Outlook.

That said - please note that creating a new user profile starts a clean slate - meaning that your current your user data (docs, pics, videos, bookmarks, etc) will NOT appear in the new profile. The purpose of this is to simply test to see if creating a new Windows user profile will work. If it does, then you will need to move your old user profile data (docs, pics, videos, bookmarks, etc) onto the new profile to make Outlook work moving forward. Explaining this process is well beyond the scope of the article and is not for the faint of heart. If you don't know what you're doing, contact me for assistance and I can do it for you.

Moving on!

To create a temporary Windows user profile, do the following:

1. Click Start, then type in "cmd" (no quotes); wait for "CMD.EXE" or "Command Prompt" to appear in the list, then right click and select "Run as administrator".
    
2. Highlight the text below using your mouse:
   
   net user Test /add
   net user Test ""
   net localgroup administrators Test /add
   echo this is a dummy line
    
3. Right click the above highlighted text, then select "Copy" from the dialogue menu.
    
4. Next, right click in the middle of the command prompt window you opened up in Step #1 above, and select "Paste". The text you copied in Step #2 should be output to the command line.
    
5. Sign out of the current user account, then sign back in as the "Test" user. Don't forget to bookmark this page so you can come back to it (note that: technically speaking, this bookmarked page will only be available in the current user profile). Press CTRL-D to bookmark this page now.
    
6. Once you are signed in as the "Test" user, attempt to Launch Outlook again. If it works, then you have your answer.

If you need help moving your user data over to a new profile, you are welcome to contact me - described next.

Additional 1-on-1 Support: From Dennis

If all of this is over your head, or if you need help getting your Outlook 365 (or any other version) to work, I can help using my remote desktop support service. Simply contact me, briefly describing the issue and I will get back to you as soon as possible.

About the author: Dennis Faas

Dennis Faas is the owner and operator of Infopackets.com. With over 30 years of computing experience, Dennis' areas of expertise are a broad range and include PC hardware, Microsoft Windows, Linux, network administration, and virtualization. Dennis holds a Bachelors degree in Computer Science (1999) and has authored 6 books on the topics of MS Windows and PC Security. If you like the advice you received on this page, please up-vote / Like this page and share it with friends. For technical support inquiries, Dennis can be reached via Live chat online this site using the Zopim Chat service (currently located at the bottom left of the screen); optionally, you can contact Dennis through the website contact form.