Microsoft Outlook is a powerful email client that offers many useful features for messaging and calendaring. However, it is prone to various issues and errors. The “Cannot start Microsoft Outlook. Cannot open the Outlook window. The set of folders cannot be opened” is one such error that Outlook users face while using the application. This error prevents the users from using the application, accessing their emails, and sending/receiving new messages. The error can occur due to different reasons. Below, we will be explaining the possible reasons behind the “Cannot start Microsoft Outlook. Cannot open the Outlook window” error and some effective solutions to resolve it.
Reasons for “Cannot start Microsoft Outlook” Error
There are several reasons that may trigger this error in Microsoft Outlook. These include:
- Corrupt or damaged Outlook profile
- Corrupt Outlook PST file
- Incompatible or faulty add-ins
- Conflict with security software, such as antivirus
- Damaged Navigation Pane
- Compatibility mode is on for Outlook
- Damaged or corrupt Outlook installation or program files
- Large or oversized PST file
- Outdated Outlook client
- Faulty Windows updates
- Insufficient system resources
- Permission-related issues
Methods to Fix “Cannot Start Microsoft Outlook. Cannot Open the Outlook Window” Error
Follow the given methods to resolve the Cannot start Microsoft Outlook or Microsoft Outlook won’t start issue.
1. Update Outlook
Installing the latest Outlook updates brings fixes and patches to the bugs in the program that might be causing the ‘Cannot open the Outlook window’ error. To update Outlook, go to File > Office Account > Office Update > Update Options > Update Now.
Outlook will check for new updates and start downloading the latest updates automatically.
If the update option is unavailable or disabled in your Outlook, you can update it manually by downloading and installing the latest build from the Microsoft site.
2. Check and Disable Compatibility Mode
Running Outlook in Compatibility Mode can also cause such issues. Therefore, make sure that Compatibility Mode is turned off for Microsoft Outlook. The steps are as follows:
- Right-click the Outlook shortcut and select Properties.
- Click on the Compatibility tab and then uncheck Run this program in compatibility mode for.
- Once done, click Apply > OK.
- Then, restart Outlook.
3. Use the Microsoft Support and Recovery Assistant
Microsoft Support and Recovery Assistant is a free tool from Microsoft that helps Outlook users troubleshoot problems with their Outlook client. When you run the tool, it performs a few tests to find what’s wrong with your Outlook client or system. Then, it provides solutions to fix the issue. The steps to use this tool are as follows:
- Download and install Microsoft Support and Recovery Assistant.
- After installation, launch the program and click ‘I agree.’
- Select Outlook from the options and click ‘Next.’
- Select Outlook Won’t Start or Other problems and click ‘Next.’
- Click ‘Yes’ and then click ‘Next.’
- Complete the wizard and apply the suggested solutions.
4. Check and Disable Conflicting Add-ins
Outlook add-ins help enhance the user experience as they offer certain features that don’t exist in the base application. Sometimes, these add-ins interfere with Outlook. As a result, you may encounter the ‘Cannot open the Outlook window’ error. You can run Outlook in safe mode to confirm if the problem is caused by add-ins. Follow these steps:
- Launch the Run tool by pressing the Windows + R keys.
- Enter Outlook.exe /safe in the input field and press the OK button.
- Select your Outlook profile and click OK. Outlook will open in safe mode.
If you can use Outlook without any issues in the safe mode, then it confirms that the Outlook won’t open issue is caused by add-ins. You can disable the add-ins to fix the problem. To do so, follow these steps:
- Go to File > Options > Add-ins.
- In the Manage menu, select COM Add-ins and click the Go button.
- In the COM Add-ins window that opens, unselect all the add-ins and click OK.
- Restart Outlook and check if the “Cannot start Microsoft Outlook” issue is resolved.
5. Reduce Outlook Data File Size
If your Outlook data file (PST) has become large-sized, then it can create problems with your Outlook. If you’re facing the ‘Cannot start Microsoft Outlook. Cannot open Outlook window’ error, you can check and reduce the size of your data file. To reduce the PST file size, you can compact the file or archive old emails.
Compact the PST File
Empty the Deleted Items folder and delete unimportant emails and other mailbox items. When mail items are deleted, they leave whitespace in the PST file. You can compact the PST file to remove this whitespace and further reduce the PST file size. The steps are as follows:
- In Outlook, go to File > Info > Account Settings > Account Settings.
- Click on the Data Files tab.
- Choose your PST file and click Settings.
- Then, click Compact Now under the General tab.
Archive Old Mail Items
By archiving old mail items (moving old mail items to a new local PST file), you can significantly reduce the PST file size. The steps to archive mail items in Outlook are as follows:
- In Outlook, click File > Info > Tools > Clean up old items.
- Then, select the Archive this folder and all subfolders option and choose the folder you want to archive.
- Make sure to choose or enter a date under Archive items older than.
- Finally, click Browse to choose a location where you would like to save the archived mail items in a PST file and click OK.
Repeat these steps to create more local archives of your mail items and reduce the PST file size. You can also split the Outlook data file manually or by using a third-party PST splitter tool.
6. Remove XML Files
Corrupt XML files in the Outlook directory can also be a reason why you cannot start Microsoft Outlook. You can remove these files to fix the problem. To do that, follow these steps:
- Press the Windows + R keys to launch the Run utility.
- Type AppData in the input field and press Enter.
- In the AppData folder that opens, go to Local > Microsoft > Outlook.
- Open the Outlook folder as per your Outlook version.
- Remove the XML files from the folder and restart Outlook.
7. Reset Navigation Pane
Outlook allows the users to customize the navigation pane, which is the leftmost pane in the main window. The “Microsoft Outlook won’t open” issue may also occur when there’s corruption in Navigation Pane Configuration File, i.e., profilename.xml. Also, customizations in the navigation pane can prevent you from starting Outlook. You can reset the navigation pane to fix the problem by following the given steps:
- Close Outlook and other applications that are using Outlook.
- Press the Windows + R keys to launch the Run tool.
- In the Run window, type “outlook.exe /resetnavpane” and press Enter.
If resetting the Navigation Pane doesn’t fix the error, you can delete the Navigation Pane Configuration File. To do so:
- Go to Start > Run.
- In the window that opens, type %appdata%\Microsoft\Outlook and click OK.
- You will be taken to the location of Microsoft Outlook configuration file.
- Search the xml file and delete it.
After performing these steps, check if the problem is fixed.
8. Repair or Reinstall Microsoft Outlook
Corrupt or damaged Outlook or MS Office program files may prevent the application from working properly and lead to errors. In such a case, repair the MS Office installation by following these steps:
- Click the Start menu or Windows button on the keyboard and then type Control Panel.
- Hit Enter when you see the results.
- After that, click Programs and Features.
- Locate Microsoft Office, right-click on it, and click Change.
- Click Yes on the next prompt (if asked).
- Microsoft Office installation wizard will open.
- There, select Repair and click Continue.
- The setup will start the configuration process to check the issues with your Outlook and other MS Office programs. Follow the prompts to complete the process and fix the issues (if any).
- Reboot your system to implement the changes done and check if Outlook won’t open issue is fixed.
If repairing MS Outlook (MS Office) does not work, you can reinstall the MS Office. For this, you need to uninstall the MS Office from Settings. After uninstalling, download the latest build from Microsoft site on your system.
9. Create a New Outlook Profile
One of the causes behind the “Cannot start Microsoft Outlook” error is the corrupt Outlook profile. You can create a new Outlook profile to resolve the error. Follow these steps:
- Go to Control Panel.
- Select the Mail option to open the Mail Setup dialog box.
- In the Mail Setup – Outlook window, click on the Show Profiles button.
- In the dialog box that opens, click Add to create a new profile.
- Enter a profile name and then click OK.
- On the Auto Account Setup screen, under E-mail Account, fill in the required details, and then choose Next.
Note: The Add Account Wizard will automatically look for your mail server settings.
When prompted, click Finish. You can see the new profile name listed in the Mail dialog box under the General tab. - Select Prompt for a profile to be used option under ‘When starting Microsoft Outlook, use this profile’, and then click OK.
- Restart Outlook.
- In the Choose Profile dialog box, select the new profile that you have created and then choose OK.
10. Repair Outlook Data File (PST)
If none of the above method works, this means that the Outlook data file (PST) is corrupt or damaged. To repair the Outlook data file, you can use Microsoft’s in-built repair tool Scanpst.exe (also called Inbox Repair tool). Here are the steps to repair PST file by using Scanpst.exe:
- Exit Outlook.
- Locate the Scanpst.exe file. If you don’t know the location of Scanpst.exe, read this: How to Find Scanpst.exe Location in Outlook 2019, 2016, 2013, 2010 & 2007?
- Double-click Scanpst.exe.
- Select Browse and navigate to the PST file that you want to repair.
- Select Start to begin scanning the corrupt PST file.
- Once the scanning is complete, a new screen will appear reporting the errors found in the file.
- Select Repair to fix the errors.
The Outlook Inbox Repair tool (Scanpst.exe) may help you repair the corrupt PST file. However, this built-in tool has certain limitations. Scanpst.exe can’t repair severely corrupt or oversized Outlook data file. To overcome such limitations and avoid the hassle of manual efforts, use an advanced PST repair software, such as Stellar Repair for Outlook to repair severely corrupt PST files of virtually any size.
Stellar Repair for Outlook is a powerful tool that can easily repair a corrupted or damaged Microsoft Outlook Personal Storage Table (PST) file, along with its content, such as journals, tasks, rules, contacts, emails, attachments, etc. This user-friendly PST file recovery software efficiently scans the damaged PST file, extracts and repairs the data, and saves the data into a new PST file. It can also export the repaired PST file directly to an Outlook account or Office 365.
Conclusion
The error Cannot start Microsoft Outlook or Microsoft Outlook won’t open error prevents you from accessing your mailbox. However, you can easily fix this error by applying the methods mentioned in this post. If the error is caused by a corrupt PST file, then you can use Scanpst.exe or a third-party Outlook PST repair tool, such as Stellar Repair for Outlook to repair the PST file and fix the problem. The third-party tool can help restore all the mail items from severely corrupt, large-sized, or encrypted PST files to a new PST file. It also provides an option to export all mail items directly to the live Exchange Server or Microsoft 365 account in a few clicks.
7 min read
7 min read
7 min read
