Resolve Microsoft Exchange OST is Not an Outlook Data File Error

Anuraag Singh | Last Modified: May 29th, 2020 | Outlook

Outlook plays a significant job in overseeing client email’s data and the best piece of this application is that it enables the users to work in offline mode with the OST file. At the point when you lose network with the Server, you can basically proceed with your work with the OST file and when the availability is built up once more, the OST file gets synchronized with Outlook. Some of the time Outlook tosses different sorts of errors. One of the basic errors is “Microsoft Exchange OST is not an Outlook data file.

Here, in this segment, you will get the most prominent solution to fix this issue. We will resolve this issue by using the manual as well as an automated solution.

On the off chance that you are getting this OST error while opening the OST file in Outlook, at that point you have to discover the OST from your PC. You can find your OST file at – C:\Users\user name\AppData\Local\Microsoft\user name\username.ost.

Reasons Behind OST is Not an Outlook Data File Error

The reason for this error is that Outlook didn’t perceive or sync the OST file with the server. It causes an error before clients that OST isn’t an Outlook data file. And because of the advanced security of Microsoft Outlook, it doesn’t permit clients to open the OST file in Outlook. These outcomes in different OST file errors in front of clients.

Try this automated software SysTools OST Converter to access and Convert inaccessible Exchange OST file to Outlook PST format. This application supports Outlook 2019 and below.

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Some of the possible reasons for this error are discussed below.

  1. The OST file might be corrupted or damaged.
  2. Synchronization issue among Outlook and the Exchange server.
  3. Unfortunate power cut may cause an OST file difficult to access.
  4. Surprising termination of Microsoft Outlook.

Manually Fix Microsoft Exchange OST is not an Outlook Data File Error

The manual procedure helps the clients to solve the OST file error. Be that as it may, the manual procedure is a time consuming and complex procedure for clients. But before using the manual procedure, clients must guarantee that they keep a backup of their OST file. Let us discuss a few steps to fix this error.

  • Go to Control Panel and select “Mail”.
  • In the Mail Setup exchange box, click on “Show Profiles… ” and pick your Outlook profile.
  • Presently, select Properties >> Email >> Exchange.
  • Snap-on change and select the “Utilization Cached Exchange Mode” checkbox.
  • Go to More Settings >> Advanced >> Offline Folder File.
  • Presently, again go to Settings and press “Disable Offline” and press “Yes”.
  • Once more, open Offline Folder Mode settings and snap-on OK.
  • After that click on Next and press Yes.
  • Go to Cached Exchange Mode Settings and select the checkbox named “Use Cached Exchange Mode” and afterward click on the OK button.
  • At long last, click on Next >> Finish >> Press Close.

Effective Solution to Fix Open Inaccessible or Corrupted OST Files 

The manual procedure may assist you in fixing your OST issues, yet it is a very complicated task for clients. Another urgent part is that clients don’t care for the insane arrangement which may cause inconvenience in the future. To fix OST issues, the client must depend on the lovable, fast, and simple to use option.

Therefore, the best option to fix this problem is using an automated solution i.e. SysTools OST Converter Tool. It is a phenomenal answer for clients by which they can without much of a stretch export whole Outlook data to PST. The utility itself clarifies the whole transformation procedure to send out the offline Outlook OST file to PST file. From that point onward, clients can easily import the PST file to Outlook by using the inbuilt option of Import/Export of Outlook.


In the present era, Outlook assumes an indispensable job in dealing with the client’s email information. Microsoft Outlook is a notable email application that permits the clients to perform tasks in offline mode. Nonetheless, there are different circumstances, where clients stall out and get an error message while using Outlook. Therefore, in this blog, we have discussed how to fix Microsoft Exchange OST is not an Outlook data file error. Moreover, we have also considered an effective solution by using a tool OST Converter to access corrupted or inaccessible OST files.