Microsoft Outlook OST File is Corrupted Error – Step by Step Guide

admin | September 14th, 2017 | MS Outlook

When you open a corrupt or damaged OST file by MS outlook or try to synchronize it with exchange server, you will face various error messages. Here is the list of errors; some of them are quite confusing to understand. For better understanding, we make use of xyz.ost file.

  • “Cannot open your default email folders. The file xyz.ost is not an offline folder file”.
  • Encounter large numbers of conflict items.
  • “Unable to expand the folder. The set of folders could not be opened. Errors could have been detected in the file xyz.ost. Quit all mail-enabled applications, and then use the Inbox Repair tool.”
  • Various errors when synchronizing Exchange Server mailbox with your OST file.
  • Cannot open particular Outlook items when offline.

Reason for OST File Corruption error are:

The Reason behind any pst file denied to accessed in Outlook are given below:

  • The Outlook will report this error when the OST file is damaged or corrupted and cannot be recognized by MS Outlook.
  • OST file may corrupt or damage by the attack of malicious programs like – virus and worms etc.

There can be different levels of corruption in Outlook OST file. And depending upon the level of damage, the user can use different methods to resolve the error. One direct method is to use a recover OST file professional tool for easy and intensely damaged OST files. The tool will give you better results with no data loss. Otherwise, the manual methods can also be used to do the same and are discussed below.


To solve this problem and prevent data loss, follow these steps below:

    1. Execute ScanOST.exe

Executing ‘OST integrity check’ tool will eliminate minor corruption issues of OST file. It cannot handle major corruption issues of OST file as well as there is a threat of losing data.

Procedure to execute Scanost.exe

    • Close MS outlook and other applications that are using it.
    • Locate scanost.exe file using directory structure c:\Program Files\Microsoft Office\Office 12
      [Note: Directory structure is different for different version of Microsoft Office and Operating System]
    • Double click on scanost.exe
    • If you setup outlook profile the tool will prompt you to choose profile, here select one profile from the profile name list that contains OST file you want to check.
    • Then you will be prompted to connect or work offline, Click Connect.
    • Select the option according to your scan preference if you want that tool will repair the error during scan then Select repair error check box. If you deselect this checkbox then the tool will create a scan log but doesn’t make necessary corrections.
    • Click Begin Scan.
    • To view the scan log open outlook, Deleted items folder contain scan log with subject ‘OST integrity check’


The above-mentioned solution is not applicable on highly corrupted OST files. In that case, Microsoft Recommends to convert the OST file into PST. MS Outlook offers an export-import option but this process is quite lengthy and also involves the possibility of data loss. Therefore using an automated solution to fix OST file is the best approach.