Outlook.OST Cannot Be Opened Error

Searching for a solution to resolve “Outlook.ost cannot be opened” error in Microsoft Outlook? Your work is done! In this article, you will get the perfect solution to easily regain your OST file database in Outlook.

Microsoft Outlook is an email client, available as a part of the Microsoft Office suite. Outlook makes the OST file, to store the user’s important database on the local machine while Outlook is not connected with Exchange Server.

The default location of the OST file is:-


Being a product of Microsoft Outlook, an OST file is referred to as the offline folder where users work freely without any hurdle created by limited or non-viable connection. Carry on working offline and you can synchronize the changes with the exchange server.

But Below mentioned are some quick-fix solutions that can help you to sort out the “outlook OST file cannot be opened” error in no time and let you proceed.

Depending on the type of account you have on outlook i.e. either an Exchange or IMAP account, this is going to tell, what type of information one can save on the OST file.

What Causes Outlook OST Cannot Be Opened error:

When dealing with outlook OST cannot be opened error, there must be some reasons behind this error. The following mentioned are some reasons that cause this error to pop up on the screen.

  • The first reason behind this outlook cannot open the OST file is inappropriate or improper installation of MS Outlook application. Any problem with installation will not allow the files to open smoothly.
  • While you are using the Outlook account, and abruptly or forcefully the outlook is terminated when the OST file is in use.
  • Sometimes this problem comes due to the issues in synchronization between the OST file and Exchange server.
  • When the outlook is deleted from the computer and your OST file is left orphaned.
  • Virus or malware infection can cause corruption or mild damage to the OST files.
  • Oversizing is still an issue with OST files that causes an error i.e. outlook OST cannot be opened.

Have a look at each of the mentioned reasons, and see which one is causing an issue for you. Once getting all the reasons, now move to the part of the solution for these reasons.

Manual Methods to Fix Default Outlook.ost cannot be opened error:-

Method 1: End entire Outlook related processes

  • Close MS Outlook program.
  • Right-click on the Taskbar menu and then click on Task Manager.
  • Go to the Processes tab.
  • Now, in the Processes tab, look for the processes Communicator, Sync, Outlook, or MAPI. If any of these processes found, select, and click on the End Process button.

Method 2: Disable Outlook Cached Exchange Mode

  • Close MS Outlook and go to the control panel.
  • Into the Control Panel, click on Mail option and then select Email Accounts.
  • Under the Email Accounts, hit a click on the Email tab.
  • Now click on Exchange account and then on Change.
  • Uncheck the use Cached Exchange Mode option under offline settings and hit Next to finish the process.

Method 3: Disable the Outlook Add-ins

Although add-ins are used to enhance the functionality of Outlook, faulty add-ins may sometimes create more trouble. Thus, disable the add-ins by launching the Outlook in safe mode by just typing outlook /safe in the Run dialog box. Try “Save and Send” and if it works, a faulty add-in is the main reason behind the error. You can also start Outlook in safe mode by following the below-mentioned steps:

  • Go to the shortcut icon for Outlook.
  • Now, press and hold the CTRL key and double-click the application shortcut.
  • Click ‘Yes’ when a window prompt appears asking if you want to start the application in Safe Mode

Method 4: Repair OST file with ScanOST.exe

Microsoft facilitates the users with an inbuilt ‘OST Integrity Checker’ tool i.e. called ScanOST.exe which helps to rectify minor corruptions in OST files. Repairing Outlook OST file with ScanOST.exe is a smart way to fix “Outlook.ost cannot be opened” error. However, this Outlook inbuilt utility is available with Outlook 2007 and lower versions only.

  • Exit the Outlook and navigate to the directory on your system where Outlook has been installed. Now, navigate to the ScanOST.exe and hit a double- click to launch it.
  • The application will prompt you to select the OST file for repair. Browse to select the OST file. If you don’t know its exact location, you can find it by typing the following in the Run dialog:


  • Now, select the appropriate mailbox and other options accordingly.
  • At last, select “Repair Errors” and click on the “Begin Scan” option to automatically check and remove the discrepancies in the OST file.


Limitations of manual methods

  • The manual methods are time-consuming.
  • It is a hard task for non-technical users as it requires some technical knowledge.
  • It doesn’t ensure security for data as well.

Automated Solution to Resolve Outlook.OST Cannot Be Opened Error

Here is the best tool to resolve the error that has been detected in the file Outlook.OST. This solution is effectively helping to save time. It ensures data protection while fixing up the error that has been detected in your file Outlook.OST. The name of this utility is eSoftTools OST Recovery Software.

To get back OST Emails, Calendar, Contacts, Tasks, Journals, and Notes items, download the recommended software for OST file recovery and Convert OST to PST file with all data.


The best benefit you get with this solution is that each & everything would be done by the company to fix the error that has got detected in your file with full safety as well as security while keeping your details & information safe with us.

This solution saves your time & provides you with the best solution so that you may run your file easily. So, you get the quality service & on-time solutions to fix the errors that have got detected in your file.


If you wish to fix the error that has been detected in the file outlook.OST then make sure you get in touch with the best service provider wherein by putting in a little bit cost, you can run your file easily. So, when you are facing the problem.

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