How to Fix “Outlook .PST cannot be Opened” Error?

When you configure your email account with POP3, it creates an Outlook data file (PST) on your local storage to download and store mailbox data from the mail server. This PST file stores all the mailbox items, such as emails, attachments, contacts, calendar, notes, and tasks. However, sometimes, this PST file becomes inaccessible, causing Outlook to display an error when you try to open it. The complete error may look like this:

“The file C:\Users\username\AppData\Local\Microsoft\user name\username.pst is in use and cannot be accessed. Close any application that is using this file, and then try again. You might need to restart your computer.”

Although the error message shows that the PST file is being used by some other application, it can also occur due to several other reasons. Below, we will discuss the reasons behind this error and see how to fix it.

Reasons for ‘Outlook PST cannot be Opened’ Error

There could be several reasons that can trigger this error in Outlook, such as:

1. Outlook.exe is running in the background.
2. PST file backup is running in the background.
3. An application conflicting with Outlook.
4. Outlook data file is locked by OneDrive.
5. Faulty or incompatible third-party add-ins.
6. Damaged or corrupt PST file.
7. Insufficient file permissions.
8. Outdated Outlook application.
9. Corrupt Outlook Profile.
10.  PST file has exceeded its recommended size limit

Methods to Fix ‘Outlook PST cannot be opened’ Error

Follow these methods in the given order to resolve this Outlook PST file error.

Method 1: Check File Permissions

If you don’t have sufficient permissions to access, read, or modify the PST file, then you may encounter the PST cannot be opened error. To verify the file permissions, navigate to the PST file, right-click it, select Properties, and open the Security tab. Ensure that your user account has Read, Write, Modify, and Read & Execute permissions for the file.

Also, under the General tab, make sure the Read-only attribute is not selected. If it is, clear the checkbox, click Apply, and then OK.

Alternatively, you can run Outlook as administrator to overcome permission-related issues.  

Method 2: Update Outlook and Windows

To fix any compatibility issues with Outlook and the mail server, you must check and update Outlook and Windows. This will bring patches and features that may resolve this issue in Outlook. The steps to update Outlook are as follows:

• Open Outlook and go to File > Office Account > Update Options.
• From the available options, choose Update Now.

• If new updates are available, Outlook will start a wizard and download the latest updates. You need to complete the update wizard.

To check and install Windows Updates, follow these steps:

• Open Settings on your system, go to Windows Update and click Check for Updates.

• If available, install the updates and restart the system.

Method 3: Check Antivirus Interference

Some antivirus or security programs scan Outlook data files (PST) in real time to detect threats. During the scan, the antivirus software may temporarily lock the PST file, preventing Outlook from accessing it.

To check if your antivirus software is causing the issue, follow these steps:

• Close your Outlook application.
• Open your antivirus software.
• Temporarily disable real-time protection.
• Restart Outlook
• Check whether the PST file opens without the error.
• If Outlook works correctly, then re-enable real-time protection again.
• Add the Outlook and PST file to the antivirus exclusion list.

Method 4: Close All Outlook-related Processes and Programs

As the error suggests, you must find and close all the programs that might have access to the PST file. To find and close Outlook-related processes that are running in the background, follow these steps:

• Right-click on the Taskbar area and choose Task Manager.

• Click on More Details and then go to the Processes tab.

• Now, find the processes by the name ‘outlook’, ‘communicator’, ‘Lync’, ‘UCMAPI’, and end them all. To end them, simply click on the process and then click the ‘End task’ button.
• Exit Task Manager and restart Outlook.

Method 5: Remove Faulty Add-ins

To check whether the error is being caused by a problematic add-in, you can start Outlook in safe mode. You can follow the below steps to do it:

• Close Outlook and then open the Run dialog box (press Windows + R keys).
• Type outlook.exe /safe and press the Enter key.

If the error disappears, it means that some faulty add-ins were causing the error. You can disable the add-ins by following these steps:

• Go to File > Options. In the Outlook Options window that opens, click Add-ins.
• In the Manage option at the bottom, select COM Add-ins from the dropdown menu and click OK.

• Uncheck all add-ins and click OK. Now, restart Outlook normally.

To find the incompatible or problematic add-in, enable one add-in at a time and restart Outlook. This way, you’ll be able to find the add-in that is causing the error. After identifying, disable the add-in and remove it permanently.

Tip: If Outlook is running in compatibility mode, it may cause issues while launching the application or accessing PST file. To disable it, right-click Outlook.exe, select Properties, go to the Compatibility tab, uncheck the Run this program in compatibility mode, and click Apply > OK.

Method 6: Move PST File from OneDrive to Local Folder

When you back up your data on OneDrive, it automatically backs up several folders, including Documents and Pictures. It might happen that your Outlook data file is in one of these folders. Microsoft doesn’t recommend placing your Outlook data file on OneDrive as it might cause Outlook errors. In this situation, you can move your PST file from the OneDrive folder to local folder and point Outlook to the file’s location. Follow the instructions below to do it:

• Close Outlook and wait for OneDrive sync to complete.
• Go to the OneDrive folder containing the PST file. If the PST file is in Documents folder, the path would be

C:\Users\[your username]\OneDrive\Documents\Outlook Files

• Copy the PST file to a new location on your local storage.
• Rename the PST file (yourname@domain.pst).
• Now, open Outlook and navigate to File > Account Settings > Account Settings > Email. In this window, select your account name and click Change Folder.

• Select your account and click the New Outlook Data File option. Now, go to the new location of PST file, select it, and click OK.
• In the Data Files tab, select the Outlook data file in OneDrive and click Remove. This will disconnect the file from Outlook.

• Close Outlook and delete the file from OneDrive, if required. This should resolve the error.

Note: After moving the PST file, you may temporarily experience Send/Receive errors while Outlook updates the new file location. To fix this, restart Outlook and verify that the correct PST file is set as the active data file.

Method 7: Create a New Profile

Corrupt or damaged profile may also prevent Outlook from accessing the associated PST file. To resolve this, you can create a new Outlook profile and remove the corrupt one by following these steps:

• Close Outlook and open Control Panel.
• Click Mail > Show Profiles and then click Add.

• Type new profile name and click OK.

• Add your email account by entering the credentials and follow the setup wizard to configure the profile.
• Outlook will connect to the server and start the synchronization. After the sync, check if all the mail folders are updated and you are able to access all the mail items.

Method 8: Repair PST File

Corruption in the PST file could also be the reason behind this error. You can repair corrupt PST file using SCANPST.exe, , which comes pre-installed with Outlook and is located in the Microsoft Office installation directory.

Steps to repair your corrupted PST file by using SCANPST.exe:

1. Close Outlook.
2. Go to SCANPST.exe location on your computer.
3. Double-click SCANPST.exe to launch it. Click Browse.
4. Select the PST file you want to repair. Click Start.
5. If errors are found, click Repair.

Note: Make sure to select Make backup of scanned file before repairing.

• After the repair is complete, restart Outlook.
• Verify whether the issue has been resolved.

What if ScanPST Fails to Repair the PST File?

Although the ScanPST can fix corruption issues in Outlook data files (PST), it may freeze, crash, or fail while repairing severely corrupted files. Additionally, during the repair process, the utility may remove parts of the mailbox data that it considers unreadable. In such cases, you can try free PST Repair Online by Stellar, which securely repairs even severely corrupted PST files up to 500 MB for free and up to 5 GB with Premium version. It does not require Outlook installation or additional software.

For advanced repair and recovery options, you can use Stellar Repair for Outlook – the desktop-based PST repair software. It efficiently repairs severely corrupted PST files with no file-size limitations, while maintaining the data’s structural integrity. The software also provides a preview of recovered mailbox items before saving. It allows you to import the repaired PST file directly into your Outlook profile/Microsoft 365/Live Exchange after repair with Technician edition.

How to Prevent “Outlook .PST cannot be Opened” Error?

You can reduce the chances of encountering this error in future by following these best practices:

• Store your PST file on your local device rather than on cloud-sync services like OneDrive, Dropbox, or Google Drive, or on network drives, as continuous syncing or network interruptions may cause file access issues.
• Avoid forcing Outlook to close or shutting down your computer while Outlook is still running as improper shutdowns can damage the PST file.
• Keep the PST file size within recommended limits by archiving older emails or using Outlook’s AutoArchive feature.
• Keep your Windows and Microsoft Office updated.  
• Use compatible antivirus software and keep it updated.
• Back up your PST file regularly.  

Conclusion

While launching Microsoft Outlook, you might encounter an error that says, “Outlook PST cannot be opened.” Although this error is usually caused when another application uses the Outlook data file, the factors/reasons listed in this guide can also cause this error. By following the troubleshooting methods in this guide, you can fix this error. If a corrupt PST file is the cause behind the issue, you can repair it using the Inbox Repair Tool or SCANPST. However, if SCANPST fails to repair the file or freezes while repairing it, you can use Stellar Repair for Outlook. This advanced tool can fix corruption issues in PST file with precision and integrity.

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