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Summary: OST files in MS Outlook are vital for offline work but can become corrupted, resulting in data inaccessibility. Kernel for OST to PST Converter offers a streamlined recovery process, efficiently restoring attachments and simplifying email searches. A trial version is available for evaluation, providing a convenient solution for OST file recovery.

An OST file stands out as a crucial feature of MS Outlook, enabling users to work seamlessly in offline mode when the Exchange Server experiences downtime. The primary purpose of an OST file is to synchronize with the Exchange Server, facilitating effective communication for Outlook users. However, the real challenge arises when OST files become corrupted, leading to potential data loss. In fact, whenever an OST file error occurs, the data stored within the OST file becomes inaccessible during these situations.

To address such circumstances effectively, users may need to perform an export of the OST file to PST format. This action allows them to regain access to their data within MS Outlook, as PST files are versatile and compatible with the application. This export to PST serves as a reliable solution for recovering and accessing data from corrupted OST files, ensuring uninterrupted productivity for Outlook users.

To provide a clearer picture, let’s consider a scenario: You’re attempting to synchronize your OST file with the server, but to your surprise, you discover that the MS Exchange Server no longer exists. Upon your attempt to access the OST file in this situation, you are confronted with an error message, as illustrated below:

“Cannot open OST file. You must access Exchange at least once to use the OST file.”

Once this error message appears on the screen, critical data such as calendar entries, contacts, emails, and other items become inaccessible. The situation becomes even more challenging when you encounter the same error repeatedly in your attempts to access the OST file. This recurrence of the error compounds the issue, making it imperative to find a reliable solution to regain access to your valuable data.

Reason of file corruption:

The real cause of facing such an error message is a user making attempt to open an orphaned OST file.


Indeed, the most ideal approach to address such OST file errors is by performing an OST file conversion to PST format. There are two methods available, one being manual and the other involving the use of a third-party tool. To manually convert an OST file to PST format, follow the instructions provided below:

  • Start on Outlook. Log in to your Exchange email server, so that you could view the contents of your OST file.
  • In Outlook, click “File,” and after that click on “Import and Export.”
  • Get on “Export to a file” and “Next
  • Click “Personal Folder File (.PST)” and “Next.”
  • Click “Personal Folders” at the top of the list, and then click “Include subfolders.”

Note: However, you got to take care while selecting and clicking the appropriate categories in the list, so that you could export only certain data such as your contacts. Click “Next.”

  • Click on the “Browse” button. Navigate down to a folder on your hard drive where you desire to store your PST file.
  • Enter a file name and after that press “Enter.”
  • Choose how you wish to manage the possible duplicate items and click “Finish.”

The manual conversion process can indeed be time-consuming and may not be suitable for all situations. To systematically and efficiently address OST file errors, users are encouraged to consider an effective third-party OST conversion software like Kernel for OST to PST Converter. This tool is designed to streamline the conversion process, ensuring that all OST data, including emails, attachments, notes, and more, can be seamlessly transformed into PST format.

Kernel for OST to PST Converter offers several valuable features, such as the ability to restore attachments, including images embedded in HTML message bodies. Additionally, it provides a ‘Find Message’ option that simplifies the task of searching for specific emails, enhancing user convenience.

Furthermore, the software offers a trial version, allowing users to evaluate its performance before making a commitment. This trial version can be a helpful way to assess whether the tool meets your specific needs and requirements, ensuring that you can make an informed decision about its usage.


The error described in the article is indeed one of the most common issues encountered by users with Exchange accounts. While manual recovery solutions like ScanPST can address some OST file problems, there are situations where they may not be effective. In such cases, deleting the account and adding it again in Outlook is a common workaround.

However, utilizing specialized OST recovery software can provide distinct advantages. With OST recovery software, you can restore OST files without impacting the account in Outlook. This means you can recover the contents within OST files, save them in PST format, and then import them back into the Outlook application. The ability to access both the recovered data and your existing account simultaneously is a valuable feature of these tools, ensuring minimal disruption to your workflow.

View the complete process of OST Conversion- Video

Kernel for OST to PST