Read time 5 minutes

Summary: Outlook data files are resistant to corruption, however, due to unexpected circumstances when these get damaged, it’s crucial to recover in time. In this guide, we will explore some possible reasons for OST file corruption and solutions to fix the corruption. We’ll also get to know about Kernel for OST to PST that recovers data from an OST file and saves it in PST format.

It’s not a matter of surprise to know the Outlook data files on your system can blow up at any time. For offline work, your emails are stored locally on your machines, including the offline storage folders (yes, you read that right).
Outlook uses an offline folder file (OST file) to allow users to work offline, even if the Outlook program gets disconnected from MS Exchange Server. The OST file is a synchronized copy (cached Outlook items) of the mailbox saved on your server. Here’s the default location of the OST file: drive:\Users\\AppData\Local\Microsoft\Outlook.

Read on to learn about the reasons causing OST file corruption and solutions to recover mailbox data from corrupt OST files.

Reasons causing corruption in OST files

Being an IT professional and system administrator, you’re responsible for managing and maintaining data storage and system integrity. It’s crucial to understand the potential reasons behind OST file corruption.

  1. Hardware-related issues causing corruption
    When the hardware installed in your premises encounters problems such as configuration error or malfunctioning, the data files can experience corruption. Some of the reasons related to hardware are specified below:

    • Bad sectors on the hard drive
      One of the most critical reasons OST files are corrupt is the presence of bad sectors on the hard drive. The issue not only severely impacts the efficient parameters but also disrupts the hard drive’s overall performance. The data files stored on the drive are also equally affected. If you often experience corruption in OST or other data files , get a review of the drive’s health and substitute it with a healthy drive as soon as possible to save your data from permanent loss.
    • Sudden power cut
      Sudden power cuts or system crashes pose a significant threat to our systems and the applications working on them. If a user is working on an OST file, there can be instances of corruption if there’s a sudden power loss or surge in the supply.
    • Network connectivity
      Routers, cables, network cards, and other network connectivity devices, if they don’t perform well, can show hiccups in the internet connection. This tends to impact the OST file accessibility, making it challenging to synchronize correctly. Therefore, ensure that you have a stable and functional connection to mitigate such risks.
    • Faulty storage device
      If the storage device installed on your system is slow performing, there might be bugs or infections causing hardware malfunctioning. This can make your Offline Storage Table (.ost) faulty.
  2. Software-related issues causing corruption
    Errors caused due to logical inconsistencies fall under the spectrum of software related errors. It includes application failure, bug transmission, or virus infections. Some software errors are hereby mentioned:

    • Conflicting add-ins in Outlook
      One common issue is conflicting add-ins in Outlook. To resolve this, disable these COM Add-ins options in the Outlook application. Here’s how: go to the File option in Outlook, then click on Options. This will open a wizard, select Add-ins, then go to Manage>COM Add-ins>Go. Here, you can disable add-ins one by one and detect incompatible ones.
    • Abnormal shutting of Outlook
      Once you finish all your work and operations with the Outlook application, make sure you exit properly. Close all the wizards and dialog boxes rather than force-shutting the application while it’s still working. The abrupt shutdown or freezing of the application can often be a reason for corruption.
    • Explicit storage limit
      Like other files, OST is also accountable for a definite storage limit of 50 GB in Outlook 2010 and upgraded versions. While the OST file size is on the way to reaching its maximum limit, it can encounter corruption or become inaccessible. We suggest you compact and split OST files regularly.
    • Faulty Outlook application
      If the Outlook application installed on your system is showing errors again and again, it might eventually cause corruption in the Outlook data files. It is challenging to identify the root cause of the problem in such situations. Alternatively, try reinstalling the application or contacting your system administrator for further assistance.
Native Solutions to Fix OST Corruption Problems

There are several manual solutions available to prevent corruption in the OST files. We have mentioned some of the proven methods to help you remove corruption from the OST files.

Solution 1: Update Folder

The method allows changing the properties of the folder (to clear offline items) to repair inaccessible OST File issues. Use the following instructions for MS Outlook 2010:

  1. Right-click any folder in Outlook and then click Properties.
  2. When the dialog box appears, click the ‘Clear Offline Items’ option under this dialog box.
  3. ‘Clear Offline Items’

  4. Click Ok.
  5. Now, click Send/Receive option in Outlook.
  6. Click Update Folder to save the changes.
  7. Update Folder to save

Solution 2: Use Inbox Repair Tool

Inbox Repair tool (scanpst.exe) is a free solution provided by Microsoft Outlook that fixes minor glitches in Exchange OST and PST files. It allows the users to scan and repair OST files on Exchange Server and MS Outlook. This inbuilt tool helps users manually fix minor corruption issues in the OST files.

Here’s the location of the utility: C:\Program Files\Microsoft Office\root\Office16

You can use the Inbox Repair tool to repair errors of OST and PST files in the later versions of MS Outlook.

Use Inbox Repair Tool

  • Limitations of Scanpst.exe tool

      Free solutions come with certain restrictions, such as:

    • Able to fix only minor corruption problems.
    • No safety assurance while recovering the data.
    • Have to run multiple times to repair the file
    • Will not work with large OST files
Solution 3: Re-create the OST file

Microsoft Exchange Server uses an offline data file (OST), a copy of information stored on the email server. If somewhere you encounter issues with the OST file, you can delete the existing one and re-create (download) that again from the server. However, use Re-create OST file procedure wisely, only if your OST file is not usable anymore. Also, there is a chance that you may lose the unsaved data if there are any.

Re-create the OST file

Solution 4: Compress the OST file

A large size OST file may cause various troubles, such as OST corruption, sluggish Outlook performance, etc. Deleting some of the items may not be viable to decrease the increasing file size. When you remove an item from the Outlook folder, it still remains in the deleted folder for a particular time period. However, deleting the item from the ‘Deleted Items Folder’ will permanently remove it from the OST file, which is losing your valuable item forever.

Another alternative to it is to compact the OST file. The OST file items are stored in such a way that they may occupy additional space and be unusable for other purposes. When you compact OST files, then it reduces that extra space occupied by the OST files.

Compress the OST file

Solution 5: Start MS Outlook in Safe Mode

Starting Outlook in safe mode disables any add-ins that may throw errors during the booting process. It allows working safely without any files or add-ins being corrupt. Simply use this command in the Run window (Press Windows key + R) command to open MS Outlook in safe mode: “outlook.exe /safe.”

outlook.exe /safe

Solution 6: Disable Anti-virus & Firewall settings

You can turn off the antivirus software and other firewall settings, as some programs (like Outlook) are designed to scan and detect problems for every incoming and outgoing email. Antivirus settings may block the normal functioning of Outlook at times, so you may try to disable the settings and restart Outlook to see the changes.

The Bottom Line

Corruption is unpredictable in Outlook data files, and it can restrict the user from performing regular operations functions. The native approaches to resolving corruption aren’t completely reliable to deal with OST corruption problems. However, a third-party solution, Kernel for OST to PST converter solution, provides a safe, secure, and swift method to recover severely affected OST files and convert OST to PST files immediately.

Kernel for OST to PST