Error Solved: “Microsoft Outlook Won’t Open or Start”

Sometimes, you may encounter a situation when your Microsoft Outlook won’t open or start and returns an error message that reads:

“Cannot start Microsoft Outlook. Cannot open the Outlook window. The set of folders cannot be opened. The operation failed.”

Cannot Start Microsoft Outlook Error Alert Box

Why My Outlook Won’t Open?

Following are some reasons that may cause Microsoft Outlook not opening issue:

• Outlook PST file is accidentally deleted or damaged
• Outlook Profile belongs to an older Outlook version
• Incorrect configuration of the application
• Improper installation of the application
• Virus or malware infection
• Internal registry conflict
• Installation of conflicting add-ins

Tip – Corruption in Outlook data file (PST) could be the reason why you cannot start Microsoft Outlook. You can repair the corrupted PST by using the built-in Microsoft repair utility but the process is time-consuming and may result in data inconsistency. Use Stellar Repair for Outlook software to repair PST file and recover all the mailbox items, maintaining data integrity.

Common Symptoms and Solutions for the Outlook won’t Start Issue

You can refer the table below to know the symptoms, likely cause behind the issue, and the right fix.

Methods to Solve ‘Outlook Won’t Open or Start’ Issue

You can’t access Microsoft Outlook emails and other items unless the ‘Outlook not opening’ issue is resolved. Let’s discuss some methods to fix this issue:

Method 1 – Update Outlook and Windows

If you are wondering why won’t Outlook open, one of the reasons is that your Outlook application or Windows OS is not up-to-date. To resolve the issue, you just need to update the Outlook application or install latest Windows OS updates.

To update Outlook:

1. Go to File > Office Account.
2. Click Update Options and then click Update Now.

Outlook Update Options

To install latest Windows updates manually (if automatic updates option is not configured), follow the given steps:

1. Go to Settings.
2. Select Update and Recovery and click how updates get installed.
3. Turn on automatic updates.

Now, try to open your Outlook application and see if the ‘Cannot start MS Outlook’ error is resolved. If not, move to the next method.

Note: In some situations, Outlook will not open if there’s compatibility issue between an installed antivirus program and Outlook. According to Microsoft, updating the antivirus problem might help fix the error.

Method 2 – Launch Outlook in “Safe Mode”

When you launch Outlook in safe mode, it starts with only the basic setup, without any add-ins. This helps you to check if a faulty or damaged add-in is causing the ‘Cannot Start Microsoft Outlook’ error.

Steps to launch Outlook in safe mode are:

• Go to Start > Run or Press Windows + R keys to open Run dialog box.

Launching Run utility

• Type ‘Outlook.exe /safe’ in the Run dialog box and click OK or hit Enter.

Note: Make sure to keep space when typing ‘Outlook.exe’ and ‘/safe’.

Running Outlook in safe mode (Outlook.exe /safe)

If Outlook starts in safe mode, a faulty add-in(s) is likely responsible for the issue. If Outlook won’t open in safe mode, skip to the next method.

To disable the faulty add-in(s), follow these steps:

• In the Outlook menu, go to File > Options.
• In Outlook Options window, click Add-ins from the left-side panel and then select COM Add-ins in the Manage field. Click Go.

Checking the installed Outlook add-ins

• Unselect all the add-ins checkboxes and select OK.
• Restart Outlook in normal mode.

If this works, enable the add-ins one-by-one and keep restarting Outlook after enabling each add-in. Doing so will help you identify the faulty add-in due to which you cannot start Microsoft Outlook.

Method 3 – Repair MS Office

Sometimes, a problem with MS Office installation might stop Outlook from responding and make you wonder why won’t Outlook open. In that case, you can use the built-in Microsoft Office repair tool to repair the program. Follow these steps:

1. Close all the running Microsoft Office applications.
2. Go to Control Panel and click Programs and Features.

Programs and Features in Control Panel

• Find your Microsoft Office version, right-click on it, and then select Change.

Find MS Office in Programs and Features

• Repair your MS Office program. However, the steps will vary depending on whether you’ve Click-to-Run or MSI-based Office installation type.

For Click-to-Run installation type, do the following:

• When ‘How would you like to repair your Office programs’ window pops-up, choose Online Repair and then select Repair.

For MSI-based installation type:

• From ‘Change your installation’ dialog box, select Repair and then hit Continue.

• Follow the instructions on your screen to complete the MS Office repair process.

Once the repair process is complete, try to launch and open Outlook. If Outlook is still not opening, move on to the next method.

Method 4 – Restore/Delete Navigation Pane Configuration File

A common reason behind “Microsoft Outlook won’t Open” error is corruption in Navigation Pane Configuration File i.e. profilename.xml. If the file size is 0 KB, this means it’s corrupt. In such a case, you can restore the file by following these steps:

• Close Microsoft Outlook.
• Go to Start > Run.

Launching Run utility from Start menu

• In the Run dialog box, type outlook.exe /resetnavpane.

Entering Outlook.exe /resetnavpane in Run input field

• Click OK.

If repairing the corrupted Navigation Pane Configuration File doesn’t fix the error, you can delete it (your .pst file won’t be affected). To do so:

• Go to Start > Run.
• In the window that opens, type %appdata%\Microsoft\Outlook and click OK.

Entering %appdata%\Microsoft\Outlook in the navigation field

• You will be taken to the location of Microsoft Outlook configuration file.

Outlook files folder

• Search the xml file and delete it.

After performing these steps, check if the problem is fixed.

Method 5 – Create a New Outlook Profile

One of the causes behind the “Microsoft Outlook won’t start” error is the corrupt Outlook profile. You can create a new Outlook profile to resolve this error. Follow these steps:

• Go to Control Panel.
• Select Mail option to open Mail Setup dialog box.

Mail in Control Panel

• In Mail Setup – Outlook window, click on the Show Profiles button.

Mail Setup dialog box

• In the dialog box that opens, click Add to create a new profile.

Creating a new profile in Mail

• Enter your profile name and then click OK.

Entering Mail profile name

• In the ‘Auto Account Setup’ screen, under E-mail Account, fill in the required details, and then choose Next.

Finishing email account creation

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 name that you have created and then choose OK.

Selecting the new profile

Now try opening Outlook. If it starts normally, it means that the Outlook profile was corrupt and resulted in the ‘Cannot start Outlook’ error.

Method 6 – Change the Default Outlook Account

If you have set up multiple email accounts in your Outlook, the program may not open if it is unable to access the associated PST file. In this scenario, you can switch the account and data file. Read on to find out how:

Note: This method works only if your Outlook can open in Safe Mode.

• Press Windows + R.
• Type outlook.exe /safe.

• Press Enter to launch Outlook in Safe Mode.
• Click File.
• Select Account Settings > Account Settings.

• Open the Data Files tab.
• Choose another Outlook data file (.pst).

• Click Set as Default.
• Click Close to save the changes.
• Exit Outlook Safe Mode.

Restart Outlook and check whether it opens without any issue.

Method 7 – Delete the Outlook Profile from the Registry

If your Outlook still won’t open, it may happen due to a corrupted profile entry in the Windows Registry. In such a situation, you can remove the damaged registry key. It forces Outlook to create a fresh profile the next time it starts. Here’s how: 

• Close Microsoft Outlook.
• Press Windows + R.
• Type regedit and press Enter.

• Navigate to the following key:
• HKEY_CURRENT_USER\Software\Microsoft\Office\16.0\Outlook\Profiles (Outlook 2016 / 2019 / 2021 & Classic M365)
• HKEY_CURRENT_USER\Software\Microsoft\Office\Outlook (Outlook 2024 / New Outlook for Windows:)

Note: New Outlook handles profiles internally via Microsoft account cloud sync instead of local profile subkeys.

• Right-click the Profiles key.
• Select Export to create a backup.
• Expand the Profiles key and identify the Outlook profile you want to remove.
• Right-click the affected profile.
• Select Delete.
• Close Registry Editor.
• Start Outlook.
• Outlook will prompt you to create a new profile.
• Complete the setup.
• Restart Outlook.

Note: Editing the Windows Registry incorrectly can damage your Windows and prevent it from functioning properly. Make sure to back up the registry before making any changes.

Method 8 – Repair Outlook Data File

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 recovery tool Scanpst.exe (also called Inbox Repair tool) or a specialized PST repair software.

Steps to repair Outlook data file by using Scanpst.exe:

• Exit Outlook.
• Locate the Scanpst.exe file.
• Double-click SCANPST.
• Select Browse and navigate to the file that you want to repair.
• Select Start to begin scanning the corrupt PST file.
• Once the scanning is complete, a new screen reporting about the errors found in the file will appear.
• Select Repair to fix the errors.

After that, you can recover the repaired items to a new .pst file. To do so, follow these steps:

1. Start Outlook.
2. Press CTRL+6. This will turn on the Folder List view.
3. Under the Folder List, you can see a list of all the recovered data folders that include Inbox, Outbox, Contacts, Sent Items, Calendar, Notes, Journal, Deleted Items, and Tasks.
4. Create a new PST file.
5. Click Lost and Found folder and drag all the recovered data items from the folder and drop them in the new PST file.
6. Remove the recovered PST file.

For more information on why you can’t Start Microsoft Outlook, refer to the Manual Guide.

The Outlook Inbox Repair tool (Scanpst.exe) may help you fix the ‘Outlook won’t start’ issue. However, the built-in tool has certain limitations. You need to perform the repair process steps manually and with extra care to avoid any error. Above all, Scanpst.exe can’t repair severely corrupt or oversized Outlook data file. To overcome such limitations and avoid the hassle of manual efforts, use advanced PST repair software, such as Stellar Repair for Outlook to repair severely corrupt PST files of virtually any size.

Steps to repair corrupt PST file by using the software:

Step 1: Download, install, and run Stellar Repair for Outlook.

Step 2: From the main interface, Browse the location of the PST file. If you don’t know the location, click Find.

Step 3: Select the PST file you want to repair and click Repair to initiate scanning.

Step 4: When the scanning process is complete, you will see a list of all recoverable files and folders in the preview window. Select the files and folders you want to repair.

Step 5: After selection, click Save Repaired File on Home menu.

Step 6: Select the desired file format in which you want to save the repaired file.

Step 7: Provide the location where you want to save the recovered files and then click OK.

Now you can import this recovered PST file into your Outlook. This should resolve the Outlook won’t start issue.

Why Choose Stellar Repair for Outlook?

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. You also get advanced features, such as:

• Repair password-protected PST files.
• Offer preview of email content, attachments, embedded hyperlinks, etc.
• Recovery of permanently deleted emails.
• Export repaired PST file directly to an Outlook account or Office 365.
• Multiple export formats for mailbox data, such as HTML, MSG, PDF, etc.

Fixes for New Outlook

New Outlook does not use local OST or PST. Instead, it stores your mailbox data directly on Exchange, Microsoft 365, or IMAP server. Therefore, Classic Outlook startup fixes do not apply to it.  

You can use the following methods to fix “Outlook won’t open” error in New Outlook.

1. End Outlook Processes from Task Manager

If a background Outlook process prevents the application from launching properly, then follow the steps below to end the processes:

• Press Ctrl + Shift + Esc.
• Locate Microsoft Outlook under the Processes tab.
• Select it.
• Click End Task.
• Launch New Outlook again.

2. Restart Your Computer

At times, temporary application or system conflicts can prevent New Outlook from opening. You can fix this by restarting your Outlook. Here’s how:

• Save your work.
• Close all applications.
• Restart your computer.

After Windows loads, open New Outlook and check whether the issue is resolved.

3. Reset New Outlook

If your application’s local settings or cached data become corrupted, then you can reset the app to restore normal functionality. Follow the instructions below:

• Open Settings.
• Navigate to Apps > Installed Apps.
• Locate New Outlook.
• Click the three-dot menu.
• Select Advanced options.
• Click Reset.
• Wait for the process to complete.
• Then, launch New Outlook.

4. Reinstall New Outlook

If resetting the application does not resolve the problem, you can reinstall it. Here’s how:

• Go to Settings > Apps.
• Click New Outlook.
• Click Uninstall.
• Restart the computer.
• Open Microsoft Store
• Install New Outlook again.
• Sign in with your account

Verify that the application opens correctly.

Conclusion 

Sometimes, Microsoft Outlook might not work or throws an error, such as ‘Outlook Won’t Open’ when you try to open the application. However, you can fix such issues easily by following the methods mentioned in this post. In case the issue is caused by to corrupt PST file, you can use Microsoft’s proprietary Inbox Repair Tool to repair it. But the tool requires manual efforts and cannot repair a severely corrupt or oversized PST file. In such a case, use a dedicated Outlook PST repair software, such as Stellar Repair for Outlook to effectively repair severely corrupt PST file with a few clicks.

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