How to Fix “Cannot Start Microsoft Outlook. Cannot Open the Outlook Window”

The “Cannot Start Microsoft Outlook. Cannot Open the Outlook Window” error appears when Outlook fails to launch properly. In many cases, the problem is related to a damaged Outlook profile, corrupted data file, navigation pane settings, or a problem with the Office installation.

Fortunately, several troubleshooting methods can help you get Outlook working again. Start with the simpler solutions and move to the more advanced steps if the problem continues.

What Causes the “Cannot Start Microsoft Outlook” Error?

Several issues can prevent Microsoft Outlook from opening correctly, including:

• A corrupted or damaged Outlook data file.
• A damaged Outlook profile.
• Incorrect Navigation Pane settings.
• An Outlook data file stored on an unavailable network location.
• A damaged Microsoft 365 or Office installation.
• Conflicts with Outlook add-ins or security software.

How to Fix “Cannot Start Microsoft Outlook. Cannot Open the Outlook Window”

Try the following solutions in order.

1. Reset the Outlook Navigation Pane

A corrupted Navigation Pane configuration can prevent Outlook from starting. Resetting it is one of the quickest solutions to try.

1. Close Microsoft Outlook completely.
2. Press Windows + R to open the Run dialog.
3. Type:

outlook.exe /resetnavpane

4. Click OK or press Enter.
5. Wait for Outlook to start.

If Outlook opens normally, the Navigation Pane configuration was likely causing the problem.

2. Repair the Outlook Data File

A damaged PST or OST file can also prevent Outlook from opening. Microsoft Outlook includes the Inbox Repair Tool, commonly known as SCANPST.EXE, which can check and repair certain Outlook data-file problems.

The exact location of the tool varies depending on your Office installation and version. You can search for SCANPST.EXE from Windows File Explorer if you cannot find it in the expected Office folder.

Once you locate the tool:

1. Close Outlook.
2. Open SCANPST.EXE.
3. Click Browse.
4. Select the Outlook data file you want to check.
5. Click Start to scan the file.
6. If errors are found, select Repair.
7. Start Outlook again after the repair finishes.

Before repairing an important PST file, it is a good idea to make a backup copy.

3. Create a New Outlook Profile

A damaged Outlook profile can cause the application to stop at startup. Creating a new profile can help determine whether the existing profile is the source of the problem.

To create a new profile:

1. Close Outlook.
2. Open Control Panel.
3. Search for Mail.
4. Open Mail (Microsoft Outlook).
5. Select Show Profiles.
6. Click Add.
7. Enter a name for the new profile.
8. Follow the prompts to add your email account.
9. Select the option to use the new profile when starting Outlook.
10. Open Outlook and check whether the problem is resolved.

If Outlook works with the new profile, the original profile may be damaged.

4. Check the Outlook Data File Location

Outlook may fail to start if its data file is located somewhere that Windows cannot access.

For example, a PST file stored on an external drive or network location may become unavailable. Check whether the drive is connected and whether you can access the location normally.

If the data file is stored on a network location, verify that the network connection is active. You should also make sure that your Windows account still has permission to access the file.

5. Start Outlook in Safe Mode

Outlook add-ins can sometimes interfere with the startup process. Running Outlook in Safe Mode starts the application without loading its normal add-ins.

1. Close Outlook.
2. Press Windows + R.
3. Enter:

outlook.exe /safe

4. Press Enter.

If Outlook opens in Safe Mode, an add-in may be responsible for the problem.

You can then open Outlook’s add-in settings and disable unnecessary or recently installed add-ins. Restart Outlook normally afterward to check whether it opens correctly.

6. Repair Microsoft 365 or Office

A damaged Office installation can cause Outlook to malfunction. Windows provides built-in repair options that can replace damaged Office components without requiring a complete reinstallation.

For Microsoft 365 or newer Office installations:

1. Open Settings.
2. Select Apps > Installed apps.
3. Find Microsoft 365 or your installed Office version.
4. Select the three-dot menu next to it.
5. Choose Modify.
6. Try Quick Repair first.
7. If the problem continues, use Online Repair.

Online Repair requires an internet connection and may take longer than Quick Repair.

If the Office installation continues to cause problems, you can also review Office Installation Error Code 1603 for additional Office repair and installation troubleshooting.

After the repair completes, restart your computer and try opening Outlook again.

7. Check for Windows and Office Updates

Outdated Windows or Office components can sometimes contribute to application problems. Installing available updates can also replace damaged or outdated components.

Open Settings > Windows Update and check for available updates. After installing the updates, restart your computer and try launching Outlook again.

What If Outlook Still Does Not Open?

If none of the previous solutions work, the problem may involve a more serious Office installation issue or a damaged Windows environment. In that situation, Office Error Code 0-1005 provides another useful reference for troubleshooting Office installation and startup problems.

At this stage, consider removing and reinstalling Microsoft 365 or Office. Before doing so, make sure you know your Microsoft account details and have backed up important Outlook data.

If the problem started immediately after installing an Outlook add-in, security application, or major Windows update, consider whether that recent change could be responsible.

Frequently Asked Questions

Why does Outlook say “Cannot Open the Outlook Window”?

The error can occur because of a corrupted Outlook profile, damaged data file, Navigation Pane configuration, unavailable data-file location, or damaged Office installation.

How do I reset Outlook’s Navigation Pane?

Close Outlook, press Windows + R, enter outlook.exe /resetnavpane, and press Enter. Outlook should then attempt to start with the Navigation Pane settings reset.

Can a corrupted PST file prevent Outlook from opening?

Yes. A damaged PST file can interfere with Outlook startup. The Inbox Repair Tool, SCANPST.EXE, can scan the file and repair certain types of corruption.

What should I do if Outlook works in Safe Mode?

If Outlook opens in Safe Mode but fails normally, an add-in may be causing the problem. Disable recently installed or unnecessary add-ins and then restart Outlook normally.

If Outlook opens in Safe Mode, an add-in may be responsible for the problem. You can then open Outlook’s add-in settings and disable unnecessary or recently installed add-ins. If the application still fails to start, see our guide to We’re sorry, but Outlook has run into an error for additional troubleshooting. Restart Outlook normally afterward to check whether it opens correctly.

Conclusion

The “Cannot Start Microsoft Outlook. Cannot Open the Outlook Window” error can usually be traced to an Outlook profile, data file, Navigation Pane configuration, add-in, or Office installation problem.

Start by resetting the Navigation Pane and checking Outlook in Safe Mode. If those solutions do not help, repair the Outlook data file, create a new profile, and repair Microsoft 365 or Office. These steps can resolve many common Outlook startup problems without requiring a complete reinstallation.