Convert OST to PST

How to fix Outlook OST error message: ‘Cannot open your default email folders, the file xxxx.ost is not an offline folder file’?

Offline data file (OST) holds essential information of Outlook mailbox that even allows user to access that information and work offline, even when an internet connection is weak or unavailable. And when the connectively is fully-available, the mailbox content is smoothly synchronized on Exchange Server, without interrupting the workflow.

But when the corruption enters to the OST files or any anomaly disturbs the synchronization process, then user is denied the access to open Outlook files. Below given is one such example of Outlook OST file error message:

‘Cannot open your default email folders, the file xxxx.ost is not an offline folder file’

When this error message is encountered, then the user is unable to open the mailbox and access the required information.

Cause of This Error Message

There could be two reasons for the occurrence of this OST error message:

  • OST file is corrupted or damaged, which is why it is not identified by Outlook.
  • Outlook is used in conjunction with Exchange Server and if Exchange is unable to access the particular mailbox then it throws such error.


Based on the information of this error message, user is unable to access Outlook mailbox. User can use this below given manual techniques to resolve this problem and get back to the normal functioning of Outlook mailbox.

Method I: Locate and Verify the File Information

To resolve this issue, you need to first search the OST files that is creating the inaccessibility troubles. Use the inbuilt search function in Windows to locate the offline data files.

  1. Locate the file, which is throwing the error
  2. Make sure that the user profile information of Outlook and Exchange server is valid.
  3. Verify the availability of internet connection at the moment
  4. In case, Outlook is working then try to rename the damaged file with another name. Then try to open the Outlook.

Method II: Verify Hardware and Software Reliability

If the problem is not resolved in the above step, then it could be because of hardware or software conflictions. Verify that all the hardware components are working properly, including routers, connectors, data cards etc.

However, if the problem still persists then jump to the next method, which is technical and requires precise implementations.

Method III: Delete and Recreate the Existing Outlook Profile

Before implementing this method, it is essential that you have taken the updated backup of your mailbox data files, prior to deleting them.

To delete and recreate the profile, follow these steps:

  1. Go to “Start” button and choose “Control Panel” and open it.
  2. Select and open “Mail” option in “Control Panel” window.
  3. In the “Mail Setup” window, select “Show Profiles” option.
  4. From the list of profiles choose the profile that needs to be removed.
  5. Select “Remove” button to delete the opted profile.
  6. Now select “Add” button to create new profile.
  7. Facilitate the relevant account information and then select “OK”.
  8. Now, launch Outlook profile and verify if the issue has resolved.

However, if the above mentioned method is unsuccessful to resolve this OST file error, then try taking the help of third-party repairing tool.

The OST to PST tool is a reliable OST file repairing tool that instantly fixes the files and recovers the total information with complete accuracy. Upon repairing the files, the software even allows you to convert OST files to PST and various other formats like DBX, MBOX, MSG, RTF, HTML, EML, TXT, MHTML, & PDF. Also, you export OST files directly to Office 365 and various other email servers and web-based email apps. Get More information, Visit here:-

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