Solved: Microsoft Exchange OST is in Use and Cannot be Accessed

Everything in this world has both pros and cons associated with it so is with MS Outlook and its data files i.e., OST and PST file. But, in this blog, we are going to talk about OST file only. The main purpose of OST file in Outlook is to let users work in an offline mode also. In two situations OST file is created in Outlook one is when a user account is connected with Exchange Server and other is when Outlook is configured with IMAP account.

How to fix “Microsoft Exchange OST is in use and cannot be accessed” is the frequently searched query over the internet from past few days. If users are facing this error again and again, then they need to understand the cause behind it.

No need to worry, this blog will update you all with the same.

Root Cause of “Microsoft Exchange OST is in use and cannot be accessed” Error

In some cases, when a user tries to use the Save and Send feature in Outlook, it displays an error message that “the file xxxx.ost is in use and cannot be accessed”. It generally means that OST file is in use by some other program also. But, there can be many other reasons also and are listed below:

1. Synchronization problem between Outlook OST and Microsoft Exchange Server.

2. Microsoft Exchange OST file is engaged with some other program.

3. More than one user tries to access the same OST file at a time.

4. Because of unreliable or slow speed internet, this error might occur.

5. Any unauthorized user tries to access the OST file, then also this error arises.

Today’s morning when I started my Microsoft Outlook 2016 account crashed. But, when I tried to start it again, the following error message is displayed:

Outlook Data File – The file C:Usersuser nameAppDataLocalMicrosoftuser namexxxx.ost is in use and cannot be accessed. Close any application that is using this file, and then try again. You might need to restart your computer.

But, when I tried to restart the system, the error message is still there. My important work is stuck in between in Outlook. Can anyone tell me how I can fix this error in a seamless manner?

Like this, there are many other users also who want to fix this error as soon as possible.

Multiple Ways to Error Message Outlook.ost Is in Use and Cannot be Accessed

There can be many manual ways available that a user can try to resolve this OST file error in Outlook. Have a look at all of them and try the suitable one.

Approach #1: Terminate All Outlook Related Processes

1. First of all, right-click on the Taskbar and choose Task Manager option

2. After that, choose Processes tab

3. Now, check for anything named like “Communicator”, “Lync”, “UCMAPI” or “Outlook“. If any such item is there, select it and choose End task button.

Approach #2: Turn Off Exchange Cached Mode

1. To begin, you have to exit Outlook first. Then, move to Control Panel

2. Then, click on Mail >> Email Accounts >> Email option

3. After that, you have to choose the email id of your choice and click on the Change button

4. Now, uncheck Use Cached Exchange Mode check box

5. Click on the Next button and then on Finish button to complete the task.

Approach #3: Take Help of Inbox Repair Tool

If any of the above approaches are unable to fix the issue, then you can try inbuilt Inbox Repair tool. It can be used to repair both PST and OST file of Outlook 2007 and above versions. This application will let users overcome the small issues of Outlook data file only. But in the case of badly damaged or majorly damaged OST file, this scanpst.exe tool fails.

Apart from all this, in most of the cases, this utility is unable to fix permanently deleted items from OST file. Therefore, whenever there is a major level of corruption in OST file, users switch to some other solution to get rid of the same. For complete information about hows does Scanpst works then the user can refer to this Repair OST file method. 

Automated Solution to Resolve The file .ost is in Use and Cannot be Accessed  Issue 

Unable to fix “Microsoft Exchange OST is in use and cannot be accessed” error using any of the above discussed manual. No need to worry, a third-party solution is suggested here that is really helpful in the same. OST file Recovery tool is one of the amazing application that let you deal with any type of corruption issue in OST file. It is capable to recover even permanently deleted items from OST file. Moreover, the application is compatible with all version of Microsoft Outlook.

Closing Words

Keeping Microsoft Outlook always in a normal working state sometimes becomes difficult for the user. It becomes more complex if Outlook data file starts creating an issue. Microsoft Exchange OST is in use and cannot be accessed is one such error that breaks the workflow of Outlook. Therefore, needs to be fixed in the best possible way. The blog above will let you all know about the same.