“Earlier I deleted my Outlook account & tried to access it again. During the deletion process, a message was shown “Default Outlook Profile.ost cannot be opened” I was in hurry, so I didn’t able to wait till the process gets completed. Now it is showing the OST file error & there are no emails, no contacts in my Outlook account. I had a number of important emails which were present in my account. Can you please suggest me a method which is available?”

“Yesterday I was using Outlook 2013 & suddenly my system gets corrupted. I perform system check. I again opened MS Outlook but it started showing me that the file default Outlook profile OST is in use and cannot be accessed. Can anyone have solution to this query?”

There are many user queries which state that they are unable to open OST file because of this error. And, when they open Outlook a message of this type is displayed. So, what we can do is to first understand what this error actually means & what are the reasons behind this error generation. Users can also go for a third party solution like MailPro+ OST to PST Converter to resolve this issue and convert OST file data into PST file format.

Know More About Outlook Data Files

MS Outlook is a desktop based email application which is used to access MS Exchange Server emails. The Outlook application saves its data items in the form of two file format i.e PST & OST. Both file format has its significant role in Outlook.

  • The Personal storage folder or the .pst file allows storing the copies of emails, calendar & other data items. It is used to store the archived items. It consumes a lot more storage than OST file, i.e approx 20 GB in Outlook 2003, 2007 and 50 GB in 2010, 2016.
  • While OST i.e the Offline storage table allow offline mode work access in Outlook. When the connection is not established between MS Outlook & Exchange Server, then this type of file is created. At that moment, OST using the cached data allow the users to work in offline mode.

Reasons Behind OST File Corruption Error

Go through the following reasons, which are responsible for OST file corruption. Here some instructions are listed below:

Software Reasons:

  1. Every file has its storage limit, once the OST is about to reach its maximum storage limit. The OST file may get corrupted.
  2. When the Outlook gets the freeze and shut down abnormally.
  3. Sometimes there is a problem arising in Outlook Program itself. It may corrupt the OST and as well as PST file also. Such kind of problems can only redress from the developer’s end.

Hardware Reasons:

  1. A virus infected storage media leads to OST file corruption because the data stored by OST is present locally on the system.
  2. When the OST file syncs with Exchange Server and during this, process get interrupted or abandoned due to the weak internet connection. The OST file also turns corrupt.
  3. The bad sectors distribution on the Hard Drive are the major reasons for OST file corruption. These bad sectors disturbed the functionality of Hard drive and files stored in it.
  4. Unexpected power failure leads to generate an error in OST file.

Manually Fix Outlook Profile .ost Cannot be Opened Error

There are following the set of instructions by which users can resolve Default Outlook Profile .ost Cannot be Opened Error. Let us have a look: Method 1:

Use Scanost.exe: This is an inbuilt utility, provided by Outlook 2007 version only. Below the guidelines mention, that, how to recover the .ost from Scan.ost.

  1. Open drive:\Program Files\Microsoft Office\(Office version) and go to SCANOST.EXE, double-click on it.
  2. Now, choose the OST file which is supposed to be repaired.
  3. A new window will be opened. It shows two option: Scan all folders and Choose a folder to scan. As per the user requirement, a user can choose the option.
  4. There also a checkbox named as Repair errors. Check the Repair errors box. If you do not check the box, then issues will be recorded but will not be fixed.
  5. Once you have done with the all steps, click on Begin Scan.

Limitation: This method is only applicable in Outlook 2007. Adding, resolve only minor OST corruption. Major OST corruption error cannot be recovered by this method. Method 2:

Use Scanpst.exe: This is also an inbuilt utility software that comes up with Outlook 2007/2010/2013/2016. It is also known named as Inbox Repair Tool. It can repair both type of file OST as well as PST. The method is given below.

  1. Open drive:\Program Files\Microsoft Office\(Office version).
  2. Go to SCANPST.EXE and double click on it or directly can open the Start and type scanpst.exe in the search bar.
  3. Browse the .ost file which is supposed to be recovered.
  4. Click on Start.

Limitation: This method is applicable almost in all the versions of Microsoft Outlook. It is impossible to recover those file that is highly damaged.

Method 3:

Use MS Outlook in safe mode: This method eliminates add-ins in the Outlook that prevent OST File Corruption.

  1. Firstly, start the MS Outlook.
  2. Hold the Ctrl key and type outlook/safe in a search bar and hit Enter.
  3. A message will pop-up that “user wants to start outlook in safe mode”.
  4. Click on Yes button.

Method 4:

Recover the Navigation Pane file: Sometimes, the corrupted Navigation pane settings also leads to Default Outlook Profile.ost Cannot be Opened error. Following are the guidelines by which user can recover the Navigation Pane.

  • Click Start and type outlook.exe /resetnavpane.

Note: Make sure there is a space between the outlook.exe and /resetnavpane.

  • Click on the file in order to format the Navigation Pane.

Method 5:

Switch off Compatibility mode in Outlook: By disable the Compatibility mode, OST file can be prevented from corruption.

  1. Open Start and type outlook.exe in the search field.
  2. After that, click right click on OUTLOOK.EXE and then click Properties
  3. A window will appear and switch to Compatibility tab
  4. Clear the check from “Run this program in compatibility mode for”.
  5. Click on OK button.

A Reliable Tool to Resolve OST File Corruption Issue

It is quite easy to resolve the minor corrupted OST file from the above-stated method. Henceforth, to solve these major issues, users can go for an impeccable third-party tool i.e. MailPro+ OST to PST Converter. It is a very dynamic and relevant solution for all end users, by which they can access their OST files easily. This tool not only recovers the data but also convert OST file into other file formats without any data loss. It has a simple and interactive interface that even a novice user can understand its layout very clearly.


While using MS Outlook, users frequently encounter the error like “ Default Outlook Profile .ost Cannot be Opened ”. Thus, here in this article, all the methods related to this error are discussed along with its reasons. If in any case user is not able to recover the file default Outlook profile OST is in use and cannot be accessed error, then it is suggested to take help from MailPro+ OST to PST Converter to repair & avoid error in the Offline OST files.