How to Use Scanost.exe to Fix Corrupt OST File?

How to use scanost.exe to fix OST errors?

One of the most widely used email client is Microsoft Outlook which provides various features over its counterparts. MS Outlook stores its database in two formats PST (Personal Storage Table) and OST (Offline Storage Table). OST allows user to work with Outlook in offline mode. It stores all offline data which has been created when the user is working in the absence of Exchange Server and hence called its local storage area. User can work on OST file and modify its content in offline mode. This OST file gets synchronized automatically with Exchange server once it gets reconnected.


At times while using Outlook, users find it difficult to connect to server ailing to various reasons which are intangible and unrecognized. These reasons could be any like power failure, hard disk failure, virus attack etc which in turn damages the OST file. Once OST file gets damaged or corrupted it becomes impossible to synchronize properly with the Exchange Server. In such conditions, it is recommended to use the inbuilt repair tool or scanost.exe which gets downloaded automatically for free with Outlook.

Scanost.exe tool performs integrity check first and can be located at Drive:\Program Files\Microsoft Office\Office_version. It does not make any changes to mailbox. It only scans corrupted OST file and mailbox and tries to restore OST file synchronization differences. It repairs the offline data file by rebuilding the header of data item and resetting the file structure. For executing it the user must be connected to Server. Following steps can be followed to execute this tool:

  • Close the Outlook application if it is running
  • Locate scanost.exe at Drive:\Program Files\Microsoft Office\Office_version
  • Double click on scanost.exe
  • You will be prompted to select a profile according to your Outlook setting. Select the profile which contains the corrupted OST file
  • Click on Connect when you are provided with the option of Connect or Work Offline
  • If you want the tool to repair the error during scan then select repair error checkbox. On deselecting this checkbox tool will create the scan log but will not repair it
  • Click on Begin scan
  • In order to view the scan log, Open Outlook, go to Deleted Item Folder and click on OST integrity check

This scan log file available under Deleted Item Folder also consists of information that tool cannot repair. If still error exist then refer to this OST to PST tool.