Hi,

Yes, this error comes when you open an OST file in MS Outlook because MS Outlook does not support opening of OST file outside of its MAPI profile. If you want to open OST file in Outlook then need to convert it in PST file format. You can convert OST file to PST file format by deploying these steps:

1. Firstly open MS Outlook and log in to your Exchange account to view OST the file contents

2. Now in MS Outlook File >>Open>>Import

3. Select "Export to a File" option and click on "Next"

4. Select "Outlook Data File(.pst)" and click on "Next"

5. Hit on "Personal Folders" at the top of the list, and select "Include subfolders" options. Click on "Next" and you can export everything from your OST file into a PST file.

6. Now click on Browse button to select the location to save data file. After selecting the location, type the name of PST file.

7. Once done, click on Finish button and get your OST data into PST file format.

You can also use Export OST to PST software to open OST file in Outlook 2013. It might save your valuable time.

OST Recovery is mostly needed in the case when your OST file data is inaccessible, The Outlook OST file data became inaccessible due to system failure or any technical reason. In that situation, you must OST to PST Converter that repairs inaccessible Outlook OST file data and makes it readable. OST to PST Converter software is user-friendly software and it is very easy to use. Only you need to download this software and install it and use it.