.OST file problem

Occasional Contributor

My pc died, but I had saved my .ost file.  I wasn't able to export my contacts from outlook.  I use Gmail with imap settings.  I installed Outlook 2021 on the new pc and connected to my gmail account and all the mail was downloaded. Now I'm unable to swap the old .ost file with the newly created one to export  my contacts and import to outlook.

Is there anyway I can extract my contacts from the original .ost file and import to outlook?

Or is there anyway to change the .ost file to .pst, then I can load the .pst file in outlook to export the contacts and import them to the new .ost file within outlook?

Thank you.

9 Replies

Yes, you can extract your contacts from the original .ost file and import them to Outlook by following these steps:

  1. Export Contacts from OST File:

  • Open Microsoft Outlook and click on the File menu.
  • Select "Open & Export" and then click on "Import/Export".
  • In the Import and Export Wizard, select "Export to a file" and then click on "Next".
  • Select "Outlook Data File (.pst)" as the file type and then click on "Next".
  • Select the Contacts folder from your OST file and choose a location to save the exported file. Click on "Finish" to complete the export process.

2. Import Contacts to Outlook:

  • Open Microsoft Outlook and click on the File menu.
  • Select "Open & Export" and then click on "Import/Export".
  • In the Import and Export Wizard, select "Import from another program or file" and then click on "Next".
  • Select "Outlook Data File (.pst)" as the file type and then click on "Next".
  • Browse to the location where you saved the exported contacts file and select it. Make sure that "Replace duplicates with items imported" is selected, and then click on "Next".
  • Choose the location where you want to import the contacts and click on "Finish".

After completing these steps, your contacts should be imported into Outlook. Note that if your OST file is encrypted or corrupted, you may need to use a third-party tool like Gaintools OST to PST converter tool to extract the contacts before importing them into Outlook. Or refer to this article to know more details: https://www.gaintools.com/how/fix-the-file-username-ost-is-in-use-and-cannot-be-accessed-in-outlook/


Thank you for responding. However, a new ost file was created when I loaded Outlook 2021 and connected to my gmail account.  All my mail downloaded at that time.  I closed outlook, moved the new ost file to another location and put the old ost file in it's place.  When I launched outlook, it gave an error to the effect that it could not connect the ost file to gmail since the ost file was configured to a different account. I tried various things to get around this to no avail.

Hence, I'm stuck without anyway to open the original ost file and export my contacts.

That being the case, your only option, at this point, is a third party tool such as the one kelvinmarkus suggested. Here's another one:


@Hal Hostetler 

Hal, I bought a converter which successfully extracted my contacts to a .pst.  However, when I go to add the .pst via File, Account Settings, Data Files, Add, I get this error when selecting Outlook data file (.pst): 

 An unknown error occurred, error code: 0x80070002.  I can't get past that to even select my pst file.  I did a full repair on Office 2021 and continue to get the same error. Researching that error did not yield any usable solutions.  

At this point, I'm stumped.


That error often means there is an issue with the .PST file. Have you tried running the Inbox Repair Tool (Scanpst.exe) on the .PST file? Instructions are here:

Using the Inbox Repair Tool (scanpst.exe)

More info on the error is here:

An Unknown Error Occurred Error Code 0x80070002 in Outlook

I get that error when I get to the New Outlook Data file window box. I then highlight Outlook data file (.pst). As soon as you click Ok, the error comes up. You don't even get a chance to browse to your data file. The same error pops up when you select iCloud from the window. Truly bizarre.
Hal, I resolved the problem. Instead of trying to add a data file, instead I did a file import. That brought in the whole pst so I simply opened the contacts, copied and pasted them to the correct contacts for my mailbox and all is now right with the world. What a time consuming effort. Thanks again to you and others who responded. Be well.

.OST file problem is due to corruption and it can be caused by various reasons such as virus attack, sudden system shutdown, etc. To fix the OST file problem, you can use various Mailvita OST to PST Converter for Mac tools available in the market. These tools help you to repair corrupted or damaged OST file and recover all the data from it. Most of these tools are user friendly and provide easy to use interface. Work on all Mac OS and Windows OS versions.



Thank you. I used another ost to pst converter to resolve the issue. Thank you.