Fix Outlook OST File is in Use and Cannot be Accessed?

Rollins Duke   
Published: May 9th, 2024 • 4 Min Read

Get complete information about query how to fix “Outlook OST file is in use and cannot be accessed” and solution to solve this error message within simple steps.

Offline Storage Table files are popular provision for business continuity within an organization yet they at times become the cause of business halting midway. This occurs mostly due to synchronization matters or because of file level corruption causing Outlook OST to drop its integrity. Although the result may not be existing or possible manually in every situation, but externally it is always likely to ensure the recovery of your Offline OST files. This segment will be clarifying the same difference in detail with potentials of recovering .ost file stuck with various errors.

Outlook OST File is in Use and cannot be accessed

What to Do when Outlook .ost Out of Access?

Solutions for the gravest of matters are occasionally hidden in the smallest of acts. Therefore, before going for big leap, one must always try workarounds, which may probably fix state like when common problem where users need to know how to fix an error “Outlook OST file is in use and cannot be accessed.”

The following workarounds can be applied in the manner to identify how to fix Outlook OST file, which is in usage.

Process 1: Kill MS Outlook Procedures

  1. Open Task Manager:
    • Right click on task bar
    • Otherwise, press CTRL + ALT + DELETE
  2. Click on Processes tab to preview all background procedures
  3. Look for any of following:
    • Communicator
    • Ucmapi
    • Outlook
    •  Lync
  4. Choose an item when found and click on the End Task button.

Process 2: Disable the Cache Mode for MS Exchange

  1. Close MS Outlook (confirm with the background processes too)
  2. Open Control Panel and select Mail option
  3. Click Email Accounts
  4. Choose Email tab
  5. Choose an email address, which provides a warning >> click on Change
  6. Uncheck option of Cached Exchange Mode
  7. Click on Finish >> Next

Other Fixture: If despite of applying the above-mentioned workarounds, you are unable to get a solution to your issue then, the problem is probably with integrity of Outlook OST file. In manner, to resolve the issue in this state, you must try executing OST integrity check by using Scanost (Scanpst in MS Outlook 2007 and above editions) utility.

NOTE: The utility is the only programmed to check for the minor level of integrity problems with Outlook OST file structure. Issues beyond all its potential of repairing may not be fixed, or even leaving your Offline OST files in the state of inaccessible.

Loss of Ease of Access: Issues with an OST

Accessibility is the most important factor with an offline storage file. These types of data files can only be retrieved when connected to its respective profile. Outlook OST profiles are bound to their MS Exchange mailbox with an encryption that allows the synchronization between them. Without this the verification, one cannot utilize their Outlook OST profiles. Sometimes the failure in the synchronization may take place because of the following reason:

  1. Unauthorized access of OST profile
  2. Disrupted internet or even server connection
  3. Occurrence of software conflict with Outlook
  4. Multiple user access on similar OST profile


OST profiles are measured as the most sensitive as Outlook PST files because of being the cached copy of MS Exchange mailbox. Numerous of reasons result in failure of Outlook OST synchronization and when not detected timely, the problem prolongs putting data integrity of the offline storage at stake. As a result, users get inquisitive to know how to fix “Outlook OST file is in use and cannot be accessed” issue, without taking a clue about the issue, which was responsible causing this state to take place. Third party solutions prove to be one of the best approach in such conditions.