Outlook PST File Corrupted

A corrupted PST (Personal Storage Table) or OST (Offline Storage Table) file can cause Outlook to crash, fail to open, or display errors like “The file is not an Outlook data file (.pst)” or “Errors have been detected in the file”. This guide walks you through repairing and recovering data from damaged Outlook data files.

Step 1: Identify Symptoms of Data File Corruption

Recognizing corruption early can help prevent data loss.

• Outlook crashes or freezes when opening specific folders
• You see error messages like “0x80040119” or “0x8004010F” during Send/Receive
• Folders appear empty despite containing messages on the server
• Outlook prompts you to run the Inbox Repair Tool at startup
• The PST or OST file size appears unusually large or shows 0 KB
• You receive a message stating “Cannot open your default email folders”

If you experience any of these symptoms, proceed with the repair steps below. Before starting, close Outlook and any other Office applications.

Step 2: Run the Inbox Repair Tool (SCANPST)

Microsoft provides a built-in repair utility for PST and OST files.

1. Close Outlook completely and verify it is not running in the Task Manager.
2. Locate SCANPST.EXE on your system:
   • Microsoft 365 / Office 2021: C:\Program Files\Microsoft Office\root\Office16\SCANPST.EXE
   • Office 2019: C:\Program Files (x86)\Microsoft Office\Office16\SCANPST.EXE
   • Office 2016: C:\Program Files (x86)\Microsoft Office\Office16\SCANPST.EXE
3. Launch SCANPST and click Browse to select your data file:

%LOCALAPPDATA%\Microsoft\Outlook\

4. Select the corrupted .pst or .ost file and click Start.
5. If errors are found:
   • Check Make backup of scanned file before repairing
   • Click Repair
6. The tool may need to run multiple passes — repeat the scan and repair up to 4 times until no errors are found.
7. Open Outlook and check whether the issue is resolved.

Step 3: Create a New PST and Recover Data

If SCANPST cannot fully repair the file, you can manually recover data into a new PST.

1. Open Outlook — after a partial repair, a folder called Lost and Found or Recovered Personal Folders may appear in the navigation pane.
2. Create a new PST file:
   • Go to Home > New Items > More Items > Outlook Data File
   • Choose a location and name for the new file
3. Drag and drop recovered items from Lost and Found into the new PST folders.
4. To extract data from a severely damaged PST, use the Stellar Repair for Outlook tool or similar third-party recovery software.
5. Once recovery is complete, set the new PST as your default data file:
   • Go to File > Account Settings > Data Files
   • Select the new PST and click Set as Default
6. Remove the corrupted PST by selecting it and clicking Remove (this does not delete the file from disk).

Step 4: Repair or Recreate OST Files

OST files are used with Exchange and Microsoft 365 accounts and can be safely recreated since data lives on the server.

1. Close Outlook.
2. Navigate to the OST file location:

%LOCALAPPDATA%\Microsoft\Outlook\

3. Delete or rename the .ost file — unlike PST files, OST files are a local cache and can be regenerated.
4. Reopen Outlook. It will automatically create a new OST file and begin syncing data from the Exchange server.
5. Allow the sync to complete fully before making changes. This can take 15 minutes to over an hour depending on mailbox size.
6. Monitor the sync progress in the lower-right corner of Outlook — it will show “All folders are up to date” when complete.

Note: Do not delete an OST file if you have locally stored items that are not synced to the server. Check for any folders marked (This computer only) before proceeding.

Step 5: Prevent Future Data File Corruption

Take these steps to reduce the risk of PST/OST corruption going forward.

• Avoid exceeding file size limits: PST files have a default maximum size of 50 GB. Keep files under this limit by archiving old mail.
• Do not store PST files on network drives: Always store them on a local disk to avoid corruption from network interruptions.
• Use AutoArchive to keep your mailbox manageable:
  • Go to File > Options > Advanced > AutoArchive Settings
  • Set it to run every 14 days and archive items older than 6 months
• Close Outlook properly — avoid shutting down your computer while Outlook is running.
• Keep regular backups of your PST files by copying them to an external drive or cloud storage when Outlook is closed.
• Run SCANPST periodically even if you are not experiencing issues, as a preventive measure.