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“Outlook.ost is in Use & Cannot be Accessed” Issue Resolved

Jaspreet Singh Devgan | Modified: 2020-10-05T10:09:48+00:00|How to | 5 Minutes Reading

The Exchange account holders who access their mailboxes locally with Outlook are very much familiar with OST files & with errors like “Outlook.ost is in use and cannot be accessed”. This file is created automatically when the Cached Exchange mode is turned on.

It also stores the exact replica of the Exchange mailbox locally & enables users to continue working even if the server is not available due to some issue. All the modifications made to the OST files are synchronized to the actual Exchange mailbox when the server comes back online. If in case, any damage is done, it leads to mailbox inaccessibility.

Various Outlook users are finding glitches in the application from time to time. The main reason behind such kind of issues can be Outlook crashes or Outlook working improperly, which leads to corruption in the OST file. However, users are not aware of how to identify the OST file which is damaged, or what is the cause of corruption & how to fix it.

Thus in this article, we are going to discuss the causes behind Outlook.ost is in use and cannot be accessed error. We will discuss both manuals as well as the automated solution to convert OST to PST so as to fix these types of errors.

How to Identify OST File is Corrupted

The most common sign of OST file corruption is the prompting of the error “default Outlook profile.ost is in use and cannot be accessed”. This error is shown when someone attempts to open Outlook or try to launch Outlook several times. Other common error messages could be:

  • Outlook.ost is in use and cannot be accessed
  • Cannot display the folder. Outlook.ost is in use
  • The OST file is being used by another application

As a user, the first thought that comes after encountering this error would be to close the application that is using this file. But, many times this may not work & even after quitting Outlook the error may flash again. Hence, it is very necessary to find the real cause of this error.

Common Reason Behind the Error

  • Faulty synchronization of OST file with Exchange Mailbox
  • Outlook running with conflicting applications
  • Illegal attempts to access OST file
  • So many users try to access the same OST file
  • With no Internet Connectivity

How to Fix Error Message Outlook.ost is in Use and Cannot Be Accessed

You can try 4 ways in which you can repair the Outlook OST file & fix this error message.

Solution 1: Convert OST All Data Items to PST

Converting OST files data into Outlook PST file format is a very useful method to resolve this error. This can be done by using both manuals as well as an automated solution.

Manual Method

Run Outlook in safe mode & then follow the below-mentioned steps:

  1. Click File >> Open >> Import
  2. Select “Import from another program or file” from the pop-up window
  3. Now, select ‘Outlook Data file(.pst)’
  4. Click Next
  5. Hit the Browse button & then select the OST file that is to be converted
  6. Now, select the option to replace, allow or ignore import duplicate items option
  7. You can provide the location where you want to save the file
  8. At last, click the Finish button.

Third-Party Tool

SysTools OST to PST Converter is the software we recommend you to use. This utility can quickly resolve Outlook.ost is in use and cannot be accessed error & converts all emails. The resultant PST file can then be imported into Outlook to access the mailbox data. In addition to this the software export the files into 7+ email types.

Solution 2: Try Inbox Repair Tool i.e ScanPST.exe

Microsoft offers an inbuilt utility i.e Inbox Repair Tool to repair damaged OST files. The utility can perform the recovery of the OST file. It is also known as the “OST Integrity Check” tool. Try the following steps to use this tool:

  • First of all Quit Outlook through the task manager if it is running
  • Now, locate scanost.exe on your PC & launch it.
  • Enter Outlook profile name when the tool asks for it
  • Select connect option
  • Now hit the “Scan All Folders” option
  • Now, opt for the “Repair Errors” checkbox to make the tool automatically check & remove the errors. If you do not select the checkbox, the utility will detect issues but will not correct it.
  • Now, click to “Begin Scan”

This tool is available in Outlook 2007 & for the earlier versions only. It is designed to overcome minor issues with OST files. For high corruption issues, you can refer to the next solution.

Solution 3: Disable Cached Exchange Mode

As it is mentioned the OST file gets automatically created when the Exchange Mode is turned on. So, switching it off might solve the issues. Follow the steps:

  • Quit Outlook through Task Manager
  • Open Control Panel >> Mail >> Email Accounts
  • In the Email tab highlight the email address which is giving warning
  • Select change
  • Also, uncheck “Use Cached Exchange Mode”
  • Now, Select Next >> Finish
  • Try to re-launch Outlook

Final Words

We are sure if none of the above methods work, then you can try the automated solution. The software can easily resolve Outlook.ost is in use and cannot be accessed error.