Solve Error: Ost is in Use and Cannot be Accessed in Outlook

Whenever Microsoft Exchange is in Cached Mode on, a replica of the mailboxes from the server gets created and is saved on the system as .ost. We can continue working with the mails even if the connectivity is broken with Exchange server.

There can be various problems that cause OST corruption problems due to which you could face error “the file is in use and cannot be accessed”.

Let’s move on and learn the cause of the error

• Issues with Synchronization between OST and Exchange Server.
• Some conflict with Microsoft Outlook.
• Try to access the same ost by multiple users.
• Unreliable network connectivity or Slow Internet connection
• Unapproved access to the OST file
• Outlook process like Office Communicator 2005/2007, LYNC, and etc. running in the background.

You may also like to read: Outlook Inbox Showing Unread Messages But None Exist

Methods to Fix “ost is in use and cannot be accessed”

After you have detected the error and found the reasons behind it, the next step resolves this error. For this, there are five approaches which will help you to understand how to fix inaccessible OST error.

Method 1: Close All Outlook Related Processes

One of the initial steps that may be helpful to fix the inaccessible errors is to stop the background Outlook process. Follow the step to perform the task.

1. Close the Microsoft Outlook safely.
2. Right click on the Taskbar > select Task Manager.
3. Choose the “Processes” tab.
4. Search “Lync“, “ucmapi”, “Communicator“ or “Outlook“.
5. If you find any of these, select the process and Click End task button.

Method 2: Disable Cached Exchange Mode

In this method you just need to disable the cache Exchange Mode by following below procedure:

1. After you close Outlook, Open “Control Panel” and choose “Mail“.
2. Select Email Accounts button > choose the Email tab.
3. Choose the Email ID >> Click on the Change.
4. Un-select the option Use Cached Exchanged Mode>> Next>> Finish.

Method 3: Disable Outlook Add-ins

Add-ins are meant to improve the functionality of any applications, be it an Outlook. But many faulty add-ins can cause your application than to benefit it. Therefore we must disable those add-ins that are harming Outlook or its files. To disable Outlook add-ins start Outlook in safe mode; by typing outlook /safe in the Run dialog on Windows. Click ‘Yes’ on dialog box asking “if you want to start the application in Safe Mode”.

Method 4: Run Scanost.exe Application

This one method is mostly opted to solve the error “ost file is in use cannot be accessed” to make OST file in readable state

1. Launch Scanost.exe
   
2. Choose the Mailbox > Select ‘Repair Errors‘ > Click ‘Begin Scan’.
3. The Repair process will your few minutes to scan hierarchy and fix the error.

Note: This method can only work till Outlook 2007.

Also Read- Fix OST File Size not Reducing after Archiving Issue

Method 5: Repair OST file with Professional Software

One of the most recommend and user choices method is to use the professional software for a quick repair of corrupted OST file. For that, you much opt for a reliable and result-oriented OST Recovery tool. The tool helps you to retrieve all your data from corrupt and damaged OST file. It also offers you to save your repaired data into another file format like OST file to PST, DBX, EML, MSG, and MBOX. This tool helps to fix Outlook OST has Reached Maximum Size error.

Final words

You can use any of the explained in this article after you have identified the error with its cause. It is very important to resolve “the file username.ost is in use and cannot be accessed” error to continue working with Outlook emails. But for a quick and better solution, choose for OST Recovery Software.

About The Author:

Simran Bhatia

Simran Bhatia is a technical content writer engaged in writing clear, concise, and SEO-optimized content. With a background in computer science and a passion for writing, I thrive to deliver complex technical content in simple layman terms.