If you are using Microsoft Outlook 2019/2016/2013/2010, it is pretty common to encounter an error OST is not an Outlook data file. By following the methods explained in the article, you can easily fix the Outlook OST error OST is not an Outlook data file.
Both OST and PST are well known data files used by Outlook email applications. Where Outlook PST and OST use both Exchange servers and POP, IMAP protocols to receive and send emails.
If you are accessing your Outlook data on IMAP server, Outlook creates an OST file to store data. OST is an offline folder file that allows you to work offline. You can easily access previously downloaded data, create new emails and manage calendar and contacts etc even if you are not connected to Exchange Server.
What are the reasons for OST error: OST is not an Outlook Data File?
You usually come across various errors like OST file cannot be opened, OST file is not an Outlook data file and etc when your Outlook fails to sync with the server.
In most cases, the issue occurs when the Exchange server doesn’t trust the Outlook OST file and doesn’t get recognized as the format in the Outlook file.
As Outlook provides advanced security to external threats, OST file cannot be opened and displays OST is not an Outlook file.
However, as the synchronization issues between Outlook and Exchange server continues, OST files get damaged or corrupt.
Troubleshoot the Error OST file is not an Outlook Data File
As soon as the user receives Outlook errors, as an immediate solution to fix the error, he would think of deleting the Outlook profile and creating the new one. Although you will be free from error, your files also will be deleted from Outlook.
You can easily avoid such a hassle situation by recreating the OST file, repairing the OST file or by converting OST to PST file. Both Manual and Automated methods are explained below.
How to Fix the Error OST is not an Outlook Data File?
Method 1: To Fix Outlook OST File Error Update Windows and Restart
Some of the Windows program may stop responding when there the OS is not updated. Therefore, to update Windows, Go to ‘Settings > Windows Update‘ and check for the Windows updates.
Now, install the pending updates and restart the system. Then start Outlook and check if the error is resolved. If not, skip to the next method.
Method 2: Repair Outlook Profile to fix OST is not an Outlook data file
OST file associated with a corrupt Outlook profile may also become inaccessible and result in this OST file error. To resolve this, you can try to repair your Outlook profile via Outlook account settings. The steps are as follows:
- In Outlook 2010, 2013, 2016 or 2019, navigate to File > Account Settings > Account
- Click the Email tab and choose your account (Profile).
- Click on the Repair
- Follow the prompts in the Repair Account
Once done, restart Outlook and check if the error is resolved. If not, you can try creating a new Outlook profile.
Method 3: Fix the Error OST is not an Outlook Data File by Recreating the OST file
To recreate the OST file, first you need to locate the OST file. The default location of the OST file on your system is
C:\Users\user name\AppData\Local\Microsoft\user name\username.ost.
If you cannot locate the OST file manually, SFWare OST to PST converter can do it for you.
Note: With manual process, there are chances of data being lost. Therefore make sure you keep the copy of the OST file.
- Open Control Panel on your PC → Mail option.
- In the Mail Setup dialog box → Show Profiles button.
- Select the default profile (Outlook) and click on Properties
- In the Mail Setup for Outlook dialog, select Email Accounts.
- Go to the Data Files tab → select Open File Location.
- It will direct you to the source directory of your OST file. Right click on the OST file and select Delete.
- Once deleted, launch Outlook to recreate the OST.
Once you launch Outlook, Outlook creates the new OST file. verify if the error still exists. If the OST file is inaccessible, the risk of exporting OST files for any changes on Outlook is high.
Therefore, to avoid such aggravating situations, all you can do is convert your OST file to PST and perform repair on PST file. This process fixes any Outlook errors and recovers deleted or lost data from the Outlook.
With SFWare OST to PST converter your task gets easier. The tool while converting OST to PST fixes all the trouble causing OST errors. Besides fixing the OST file error, the tool also recovers lost data from its attributes such as emails, tasks, contacts, notes, RSS feeds. Furthermore, by converting the OST file, severe OST corruption gets fixed during reorganizing the structure to PST file format.
Convert OST to PST to Fix OST error
Download and Install SFWare OST to PST conversion software on your computer. Run the tool.
- Two options Open OST file and Find OST file are displayed on the main screen
Open OST file: select this option to repair inaccessible, corrupt or damaged Outlook OST file
Find OST file: select this option when you’re not aware of the OST file location. The tool will automatically find the OST file
- Click on Browse to store the converted OST file
- The software will start the OST to PST conversion and will generate a healthy PST file which is ready to use.
Now, you will have a PST file that contains all your Outlook items that were saved in an OST file. By importing this PST file into your Outlook you can successfully access all Outlook attributes.