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OST is Not an Outlook Data File Error: 5 Ways to Fix It

Users need the OST file to synchronize offline data

4 min. read

Updated onOctober 4, 2023

updated onOctober 4, 2023

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Key notes

OST is not an Outlook data file is an error that users complain about using the Outlook app, and it may occur for several reasons. However, this article will discuss the cause of the error and how you can fix it.

Microsoft Outlook is one of the best tools for managing personal information such as webmail, contacts, calendar entries, and lots more.

It has many features that make it better than other software in the market. One of the advantages of using Outlook is that users can work on it when offline.

Though you need an internet connection to connect with Outlook servers, users can work offline and sync it later whenever there is an internet connection.

Furthermore, using Outlook without a network connection enables the Offline mode. It works with an OST file (Offline Storage Table), an Offline Outlook data file used to store your activities while disconnected from the servers.

Hence, the copy saved on the OST file is synchronized with Outlook when there is an internet connection.

Is Outlook OST a data file?

Outlook OST is an Offline Outlook Data File that allows you to store all the work you have done while offline. It contains a synchronized copy of mailbox information on a local computer.

So, without the Outlook OST data file, users won’t be able to synchronize the offline Outlook data.

Users can convert OST files to PST files. However, it may be for reasons such as exporting or accessing the OST file on another computer or exporting it for someone else to use.

Hence, we recommend you read our article aboutsaving your Outlook emails using OST to PST Converterfor more information.

How do I fix OST is not an Outlook data file?

1. Recreate the OST file manually

It will help fix the Outlook data file.ost cannot be opened error.

2. Delete the OST file

After the process is complete, launch Outlook. It’ll automatically recreate the OST. It is the best fix for fixing the error message:The set of folders cannot be opened – the file is not an Outlook data file.

3. Use an OST Converter Application

Exporting the OST file to PST allows the user to import the PST file into the Outlook application.

4. Restart your PC

Restarting the PC will fix startup issues affecting the file.

5. Update Outlook on your PC

What is the difference between .PST and .OST in Outlook?

Outlook PST Files can store local copies of your email data. Also, users can export and import tasks, messages, contact, etc., to any PC.

However, Outlook OST files allow you to store work done in offline mode and can only be synchronized individually using Outlook servers. Likewise, exporting is not possible unless converted to PST.

In conclusion, we recommend you read our article aboutsaving your Outlook emails using OST to PST Converterin a few minutes.

Also, you can go through our guide onrecovering deleted/archived Outlook messagesto retrieve your data.

OST is Not an Outlook Data File Error: 5 Ways to Fix It#

Is Outlook OST a data file?#

How do I fix OST is not an Outlook data file?#

1. Recreate the OST file manually#

2. Delete the OST file#

3. Use an OST Converter Application#

4. Restart your PC#

5. Update Outlook on your PC#

What is the difference between .PST and .OST in Outlook?#