How to Repair Microsoft Outlook PST or OST File

You are experiencing errors or malfunctions in Microsoft Outlook and you suspect that the problem may be caused by a corruption in your Personal Folders file, which contains all your email and other content. To help locate the cause of the problem, Microsoft offers a built-in inbox repair tool, also known as ScanPST.

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The ScanPST tool can scan a Personal Storage Table, PST, or Offline Storage Table, OST, file to diagnose and repair errors in the file. These file formats are used in Outlook to store data locally for personal backup and offline access, respectively. If the tool detects any corruption, it offers to fix the errors. How it works

Before it tries to repair a file, the tool automatically creates a backup. However, you may want to back it up as an extra safety precaution. To find the location of the PST or OST file, open Outlook and click the File menu. Click the Account Settings button and then select the Account Settings command.

In the Account Settings window, click the tab for Data Files. Check the path of the file you want to scan and open it in File Explorer. Close Outlook. Then, simply make a backup copy of the file. If you get an error about a file being locked when you try to back it up, make sure Outlook and any applications that use or integrate with Outlook are closed. If necessary, open Task Manager to check the programs that need to be closed.

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In File Explorer, browse to the folder that contains scanpst.exe to launch the tool. The location varies slightly based on your flavor of Outlook and whether it’s a 32-bit or 64-bit version. For the 64-bit version, start by browsing to C:\Program Files\Microsoft Office\. For the 32-bit version, browse to C:\Program Files (x86)\Microsoft Office\. From there, drill down to the following locations:

Microsoft 365, Outlook 2021, Outlook 2019, and 2016 – ..\root\Office16.

Outlook 2013 – ..\Office15

Outlook 2010 – ..\Office14

Outlook 2007 – ..\Office12

If you can’t find the file with a specific path in File Explorer, just search for scanpst.exe. Double-click the file. The window lists the path to the PST or OST file. If it is pointing to the wrong file, click the Browse button and select the correct file.

With the correct PST or OST file entered, click the Start button. This tool goes through eight steps. Assuming the file is corrupt, the tool will stop at some point and tell you that it has found errors in the file. Clicking the Details button may or may not provide more information. Either way, click the Repair button.

The tool will then display a notice telling you when the repair will be complete. Click OK. Run the tool again to see if your PST or OST file now passes the test. If additional errors are found, click the Repair button again.

At some point, the tool may indicate that it has found only minor inconsistencies in the file and that repair is optional. Instead of fixing it again, you might want to check the app’s log file to see the scan results.

To do this, navigate to the folder containing your PST or OST file. Double-click the log file that starts with your mailbox name. The log file contains plain text, so you can read it in Notepad or a similar text editor. Then, open Outlook and try to replicate the behavior that caused the problems in the first place.

If Outlook is working properly, you’re set. If not, you may want to try other repairs or consider other causes of errors affecting Outlook.

How can I tell if my PST file is corrupt?

Common indicators of corrupted PST files include:

• Error messages, such as “File [filename].pst cannot be opened.
• Outlook fails to open or crashes when accessing the PST file.
• Emails, contacts, or calendar entries are missing or cannot be accessed.
• Delay in opening or navigating to folders saved in PST file.

Emails show strange characters or incomplete data.

See: How to Scan and Repair Corrupt System Files in Windows 11

How can I prevent future PST file corruption?

Corruption in PST file can be prevented by following best practices.

• Keep PST files as small as possible: Archive old emails, delete unnecessary items, and split large PST files into smaller files.
• Close Outlook properly: Click File > Exit, and don’t shut down your computer suddenly while it’s running.
• Install the latest Outlook updates and antivirus software: Keeping software up-to-date ensures bug fixes, while antivirus software prevents malware that can corrupt PST files.
• Upgrade faulty or unreliable hardware: These include hard drives or USB drives for storing PST files.
• Enable automatic archiving: AutoArchive reduces the size of your active PST file by moving older items to the archive.
• Do not use PST files to process large amounts of data: For example, frequent import/exports and large attachments.

How can I repair PST files without ScanPST?

You don’t need to use ScanPST to repair damaged files. An alternative method is to create a new PST file and then import the data.

1. Go to File > Account Settings > Data Files > Add, then select “Outlook Data File (.pst)” and save the new file.
2. Go to File > Open & Export > Import/Export and select “Import from another program or file”. Then, select ‘Outlook Data File (.pst)’.
3. Browse to your damaged PST and select “Do not import duplicates”, then complete the wizard to transfer any recoverable data to the new PST file.

If you have a damaged PST file, you can also restore it from a recent backup.

Sometimes, the corruption is limited to some add-ins or settings rather than the PST file itself. In this case, you can access your uncorrupted file in Outlook’s Safe Mode, where such settings are disabled. Press Windows + R, type outlook.exe /safe, and press Enter to launch it, and if you can access your data, consider disabling problematic add-ins.

Fiona Jackson updated this article in January 2025.