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Summary: This guide covers Outlook issues tied to OST files, emphasizing the “missing .ost file” error in Outlook 2019. It explores causes and solutions, including Kernel OST to PST Converter as a powerful tool for repairing and recovering corrupt OST files.

Numerous Outlook issues are associated with OST files, including the most recent Outlook version, which is Outlook 2019. In this discussion, we will focus on scenarios where users encounter difficulties initiating or opening Microsoft Outlook 2019, often due to the “missing .ost file” error.

An Exchange account employs an Offline Outlook data file, which serves as a storage repository on the local system where Outlook is installed. This file maintains a synchronized copy of Exchange mailboxes, granting users access to previously downloaded emails, contacts, and more, even when offline. Server connectivity is solely necessary for sending emails and retrieving new ones.

Note that it’s not possible to transfer an existing .ost file to another system. However, you can generate a new .ost file on a different system simply by configuring the Exchange account on that system.

Why is Outlook not able to locate the .ost file?

If you’re confronted with the issue of Outlook data being inaccessible due to the “missing .ost file” error, it’s essential to understand why this occurs. The most prevalent causes of this error include:

  • Network connection or Outlook configuration issues
  • Unexpected shut down of the system or the application
  • Hardware failures
  • The intervention of third-party add-ins
  • Recent Office updates
  • Corrupted OST file

The above issues are not the only reasons for the problem which you are facing. Still, you can troubleshoot the issue by trying different solutions.

Let us troubleshoot and fix the issue of “missing .ost file.”

Check the Network Connection/Configuration Settings

Ensure that both the server and network connection are free from any problems. Additionally, verify that the configuration settings are accurate.

Check and Replace Hardware Connections

If the problem has emerged following the attachment of any recent hardware, examine for external hardware components and disconnect them if they are not essential for your system. If a hardware component is necessary, verify its authenticity and replace it with a new one if it is found to be damaged.

Remove/Disable faulty Outlook add-ins

Third-party add-ins have the potential to disrupt applications such as Microsoft Outlook and its synchronization processes. Therefore, attempt to identify and uninstall any problematic add-ins from your Outlook application.

To disable faulty add-ins in Outlook program, perform these steps in the given order.

  1. Run Outlook in safe mode using outlook.exe /safe in the Windows Run box.
  2. Run Outlook in safe mode

  3. Select the Outlook profile to launch the application further.
  4. If you see that the application is running fine in the Safe mode, then add-ins are faulty, you need to remove or disable it.
  5. On the Outlook application interface, move to File>Options>Add-ins.
  6. Move to the right panel of the Outlook interface and under View and manage Office Add-ins, select COM Add-ins against Manage option, and then click on Go option.
  7. COM Add-ins

  8. On the next dialogue box, unselect all the add-ins checkboxes and then click OK.
  9. unselect all the add-ins

  10. Exit the Microsoft Outlook application.
  11. Restart the Outlook 2019 application.

Note: If the Outlook application launches successfully after following the previous steps, it can be inferred that one or more add-ins were responsible for the issue. You can identify the problematic add-ins by enabling them one at a time and then restarting the application.

Un-install Recent Updates to the Office Program

It’s well understood that updates are typically introduced to incorporate the latest features, services, bug fixes, and more. However, it’s worth noting that certain updates can have an adverse impact on the program.

If you encounter the Outlook error following a recent update, it is recommended to reinstall the previous version of the program. Once the installation is complete, restart the Outlook application.

Repair Corrupt Outlook Data Files

As we stated, one of the reasons for this issue could be corruption in the .ost file. In that case, we should repair the corrupt OST file. We can do it on our own utilizing the utility scanPST.exe.

This application scans and rectifies errors in both the Outlook Data Files (.ost and .pst). It is capable of repairing minor corruption issues in files, but it is restricted to files with a size of up to 2 GB.

The default location of this utility is – C:\Program Files (x86)\Microsoft Office\root\Office16

And the default location of the Outlook data file is – C:\users\username\Documents\Outlook Files

  1. First, it is advised to take a backup of the Outlook data files as a precautionary measure. Then users can go to the default location and double-click on the scanPST.exe to launch it.
  2. In the opened application, click on Browse to add the .pst or the .ost file to scan for the errors. Click on Start.
  3. scan for the errors

  4. The scanning of the added Outlook data file will get started. After the scan completion, you can view the error and its details.
  5. Next, click on the Repair option to fix the errors found in your data file.
  6. fix the errors

  7. Exit the application once the repair is completed
Recreate OST File

Recreate OST file is another way to fix the issues with the Outlook application. The process of recreation of .ost file is like this.

  1. Close the Microsoft Outlook application.
  2. On the Control Panel of your system, click Mail option.
  3. Then on the Mail Set-up page, click on Show Profiles option.
  4. Select the Exchange account profile and click on Properties. Click on the Email Accounts tab.
  5. From the Email tab, select the Exchange account and click on the Change option.
  6. On the Change Account page, make sure that the Use Cached Exchange Mode option is selected. Then click on the More Settings option.
  7. Switch to the Advanced tab and click on the Offline Folder File Settings option.
  8. Move to the File section and enter the .ost file path. Click OK.
  9. Provide a different .ost file name when prompted and click OK.
  10. Finally, click on Finish and exit the Mail Set-up.
  11. Start the Outlook application now. This time a new .ost file with synchronized Exchange mailboxes will be created automatically.

We genuinely hope that these solutions prove effective for you, enabling you to regain access to Exchange mailboxes in Outlook through the assistance of the .ost file.

If the previously mentioned methods do not resolve the issue, we recommend giving Kernel OST to PST Converter tool a try. This tool is capable of repairing .ost files that may be corrupted to any extent. Furthermore, it assists in recovering specific data from .ost mailboxes and converting it to .pst file format, ensuring the data remains secure and can be imported into Outlook at any time. It is indeed an effective solution for repairing and recovering .ost file data.

Therefore, consider using this efficient and dependable OST to PST converter utility as your ultimate solution.

Good Luck!


OST file errors can be unpredictable and may arise from various factors, including network problems, problematic add-ins, hardware issues, abrupt system shutdowns, and corrupt OST files, among others. This blog provides comprehensive insights into one specific error, offering manual solutions for resolution. Additionally, a smart and dependable utility for recovering OST file data is recommended as a solution.

Kernel for OST to PST