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Know How to Fix “Outlook OST File is in Use and Cannot be Accessed” Error

Updated on August 22, 2016

Offline Storage Table files are successful provision for business continuity within organizations yet they sometimes become the reason of business halting midway. This happens mostly because of synchronization issues or due to file level corruption causing the OST to lose its integrity. Although the solution may not be available or possible manually in every case, but externally it is always possible to ensure the recovery of your OST files. This segment will be explaining the same difference in detail with the possibilities of recovering OST file stuck with errors.

What To Do when OST Out of Access?

Solutions to the gravest of issues are sometimes hidden in the smallest of acts. Therefore, before going for the big leap, one should always try the workarounds that may probably fix the situation like when the common issue where users want to know how to fix “Outlook OST file is in use and cannot be accessed” error.

The following fixtures can be applied as a workaround in order to know how to fix Outlook OST file that is in use.

Number 1: Kill Outlook Processes

  1. Open the Task Manager:

    1. Right click on the task bar

    2. Or, press CTRL + ALT + DELETE

  2. Click on the Processes tab to view all the background processes

  3. Look for any of the following:

    1. Communicator

    2. Ucmapi

    3. Outlook

    4. Or, Lync

  4. Select the item when found and click on End Task button

Number 2: Disable Cache Mode for Exchange

  1. Close Microsoft Outlook (confirm with background processes too)

  2. Open the Control Panel and choose Mail option

  3. Click on Email Accounts

  4. Select Email tab

  5. Select the email address that gives out the warning and click on Change

  6. Uncheck the option Cached Exchange Mode

  7. Click on Finish followed by Next

Other Fixture: If despite applying the above-mentioned fixtures, you are unable to attain a solution to your problem then the issue is probably with the integrity of the OST file. In order to resolve the problem in this condition, you must try running OST integrity check using scanost (Scanpst in Outlook 2007 and above versions) utility.

NOTE: The utility is only programmed to check minor level of integrity issues with the OST file structure. Problems beyond its potential of repairing may not be fixed, leaving your OST file in an inaccessible state.

Loss of Accessibility: Issues with OST

Accessibility is an important factor with offline storage files. These types of files can only be accessed when connected to their respective profile. OST profiles are bound to their Exchange mailbox with an encryption, which enables the synchronization between them. Without this verification, one cannot access their OST profiles. Sometimes this failure in synchronization also takes place due to the following reason:

  1. Unauthorized access of the OST profile

  2. Disrupted internet or server connection

  3. Software conflict occurrence with Outlook

  4. Multiple user access on the same OST profile

Conclusion: OST profiles are considered more sensitive than PST files due to being cached copy of the Exchange mailbox. Plenty of reasons result in the failure of OST synchronization and when not detected timely, the issue prolongs putting the integrity of the offline storage at stake. As a result users get curious to know how to fix “Outlook OST file is in use and cannot be accessed” issue, without having a clue about the factor that was responsible causing this situation to take place. Third party OST to PST Free solutions prove to be the best approach in such circumstances.


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