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

Microsoft Outlook stores the mailbox data either in OST or PST file format. The Personal Storage Table (PST) file is created by default when you add or configure a POP account in MS Outlook. The PST stores all the mailbox items, such as emails, attachments, contacts, calendar, notes, etc.

However, sometimes, PST file becomes inaccessible and throws an error, such as Outlook PST is in use and cannot be opened, when you try to open or access the file. 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.

While it may appear that the PST file is being used by some other application, the error can also occur due to various 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 running in the background
3. Some software conflicting with Outlook  
4. Faulty or incompatible third-party add-ins
5. Damaged or corrupt PST file
6. Lack of fie permissions
7. Outdated Outlook application
8. Corrupt Outlook Profile

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

Lack of permissions can prevent Outlook from accessing, reading, or modifying the PST file, leading to the PST cannot be opened error. To overcome this, you need to ensure that you have correct and sufficient permissions to access the PST file. Follow these steps:

• Navigate to the folder where PST file is stored. Usually, it is located at C:\Users\<Your Username>\Documents\Outlook Files or %localappdata%/Microsoft/Outlook.
• Then, right-click on the PST file and choose Properties.
• Make sure Read-Only is not checked. If checked, uncheck it and click OK.

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

Method 2: Close All 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 3: Open MS Outlook in Safe Mode and Remove Faulty Add-ins

By opening Outlook in safe mode, you can find if the problem is caused by some faulty add-ins. The steps to open Outlook in safe are as follows:

• Close MS Outlook and then press Windows + R.
• Type outlook.exe /safe and press ‘Enter’.

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 > Add-ins and disable all add-ins.
• Then, launch Outlook.

Now, start enabling add-ins one-by-one to spot the faulty one. Then, remove the faulty or incompatible add-in to fix this issue permanently.

Method 4: Disable Compatibility Mode

If Outlook is running in compatibility mode, it can prevent you from opening or accessing the PST file. To check and disable the compatibility mode, follow these steps:

• Find Outlook.exe file, right-click on it, and choose Properties.
• Under the Compatibility tab, make sure ‘Run this program in compatibility mode’ is unchecked.
• Click OK and restart Outlook.

Method 5: Create a New Profile

Corrupt or damaged profile may also prevent Outlook from opening 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 email 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 6: Update Outlook

To fix any incompatibility 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 a new update is 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, go to Windows Update and click Check for Updates.

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

Method 7: Fix PST File Errors with SCANPST.EXE

If the above methods fail to resolve the Outlook PST error, there could be a problem with the PST file itself. The PST file might be damaged or corrupted. However, MS Outlook comes with SCANPST.EXE or Inbox Repair Tool, located in the MS Office installation directory. The utility helps to repair damaged or corrupt PST file. By repairing the PST file, you may resolve the Outlook PST file error. The steps to repair PST file using SCANPST.EXE are as follows:

• Quit MS Outlook and go to the installation directory of MS Office. It is usually located at: C:\Program Files\Microsoft Office\ OfficeXX or C:\Program Files (x86)\Microsoft Office\OfficeXX.
• Find and launch SCANPST.EXE utility.

• Click ‘Browse’ and choose the PST file.
• Click ‘Start’. This will scan the PST file and check for errors.
• If errors are found, the utility will display the ‘Repair’ button, click on it, and wait for the repair to finish.

During repair, you may find the Inbox Repair Tool ‘Not responding’. However, do not close it as this is how the utility works. If the utility does not exit the ‘Not responding’ status or crashes and stops working while repairing the PST file, you can use a more advanced PST repair software discussed in the next method.

Method 8: Repair PST using Advanced PST Repair Tool

If the Inbox Repair Tool fails to resolve the error, you can download, install, and run a much more advanced and powerful Outlook PST repair tool, such as Stellar Repair for Outlook. This software repairs the PST file and restores all the mailbox contents to a new usable PST file that you can import into Outlook. You can also export the mail items from the repaired PST file to a Microsoft 365 or live Exchange mailbox in a few clicks with complete integrity and precision.

For detailed steps on repairing PST file, refer to Microsoft’s Manual Guide.

Conclusion

By following this guide, you can fix the common PST file errors, such as Outlook PST cannot be opened. However, if the error is not fixed by applying the manual methods, you can repair the PST file by using an advanced Outlook PST recovery software, such as Stellar Repair for Outlook. With this advanced tool in hand, you won’t need any other product to fix any minor or major PST file issues in MS Outlook on Windows.

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About The Author

Ravi Singh

Ravi Singh is a Senior Writer at Stellar®. He is an expert Tech Explainer, IoT enthusiast, and a passionate nerd with over 7 years of experience in technical writing. He writes about Microsoft Exchange, Microsoft 365, Email Migration, Linux, Windows, Mac, DIY Tech, and Smart Home. Ravi spends most of his weekends working with IoT (DIY Smart Home) devices and playing Overwatch. He is also a solo traveler who loves hiking and exploring new trails.