Don’t repair ost-files with scanpst.exe

Although it works for some errors, scanpst.exe is not intended to be used with ost-files.

Aside from some IMAP configurations in Outlook 2013, 2016, 2019, or Office 365, the ost-file only contains cached data and its better to start with a fresh cache again instead of attempting to fix it.

Let Outlook rebuild the ost-file

The recommended approach to deal with corruptions in ost-files it to rename the ost-file to .old when Outlook is closed and have Outlook rebuild the ost-file from the server again. This is the most reliable way and also part of the reason why there is no longer a scanost.exe (since Outlook 2010).

By default, your ost-file is located in the following location:

• C:\Users\%username%\AppData\Local\Microsoft\Outlook\

You can paste the path mentioned above in the Address Bar of Explorer to quickly open the (hidden) folder location.

Repair when rebuild currently isn’t an option

If that's not possible at the moment, because you have for instance a large mailbox and currently have a slow or expensive connection, then you can of course still give scanpst.exe a try.

For instructions using scanpst.exe see the guide: Using the Inbox Repair Tool (scanpst.exe).

Third party solutions

When all you have is an ost-file and scanpst.exe can't fix it and you can't access your email account via Outlook at the moment anymore either (or use Outlook on the Web (OWA) as an alternative), then you could consider using a 3rd party repair and recover utility which can convert your ost-fle into a pst-file.

There are various tools out there which claim to be able to do this but not all of them are legit. Trustworthy tools which I’ve used before are:

• Kernel for OST to PST Conversion
• Stellar Converter for OST
• DataNumen Advanced Exchange Recovery

As some corruptions are more severe than others, all of them offer a trial mode to see if they can actually recover the data from your ost-file and can convert the data into a usable pst-file.