How to Solve OST File Cannot be Opened in Outlook 2016, 2013

Are you frustrated with the same problem I suffered a year back? Then read the article till the end to get the ideal solution to fix OST file cannot be opened error in Outlook 2016, 2013, 2010, and other lower versions.

Outlook, which is a service from Microsoft, sometimes suffers from bugs and system issues. And their team tries to resolve them from time to time. However, the problem resides for a long time, which makes us feel irritated while working there.

Well, no longer. Here we have some fantastic ways of solving the “OST file cannot be opened in Microsoft Outlook” issue. So, let’s move right in.

What are the major causes behind OST file cannot be opened error?

Ost files are those files that help us to access contacts, emails, and calendars without connecting to the Microsoft exchange server. So, you can work on your emails while traveling, and after you connect to the network, you can easily send or receive files.

Sometimes the error shows due to a massive data file, and you can solve that either by compressing or deleting the file. To do so, visit the file>account setting>data files. Here you will find the location of that file showing corrupt errors.

Otherwise, when the system couldn’t upgrade to the latest version correctly, we face the error that ‘ost files won’t open in outlook 2016’.

Further, some other OST file related issues in outlook involved,

  • Outlook cannot run.
  • The username.ost cannot be opened.
  • The file outlook.ost is in use and cannot be accessed.
  • The set of folders cannot be accessed.

The root cause is usually the same in all cases. In the current one, the error shows when,

  • you are working in a system, and the error shows, and you tried to use the same file in another IP address simultaneously.
  • During the operation, if your network has poor or unreliable connectivity.
  • Further, some software related conflicts such as synchronization, power failure, or sudden termination of the program are also a cause of why ost files cannot be opened in Outlook 2016.
  • If your hard drive contains bad sectors, then also the problem arrives.
  • Another big reason for “ost files cannot be opened” is the presence of malware or viruses in your system.

Knowing the reason for a technical problem is the way of solving that. Now let’s see various options to fix this issue.

Also Read: OST vs PST – What is The Difference Between an OST and PST File?

Ways of fixing OST file cannot be opened in Outlook 2016

There are two ways of solving this problem: one is manually, and another is automatic.

Manual way:

After troubleshooting the reason for the problem, now you should go for some manual techniques to resolve the issue. Some of those techniques are explained below with step by step guide;

Fix:1- turn off outlook cached exchange mode

  • End all processes in Outlook.
  • Visit the control panel.
  • Go to the taskbar menu and by right-click go to task manager.
  • Now click on the Email tab in the email accounts option.
  • Select the exchange account.
  • Now click on exchange.
  • Look for the option ” use cached exchange mode” and uncheck. You can find this under offline settings.
  • Click on next to complete the process.

Fix:2- Disconnect from outlook add-ins

Often, conflicts remain within add-ins, and therefore you should try disabling them one by one to know whether it works. Operate outlook on safe mode in order to get rid of add-ins related issues.

Fix:3- Stop working processes on the outlook.

  • Wherever you are using outlook, either in exchange, office 365, or, close the email program first.
  • Now visit the control panel.
  • Here, you will get a taskbar menu.
  • Choose the task manager after right-clicking on the taskbar menu.
  • Now, visit the processes tab.
  • From the processes tab, find out processes like communicator, Lync, outlook, or Ucmapi.
  • If you can see any of them, select the end process option.

Automated way to Fix Microsoft OST file cannot be opened error:

Manual methods are always time-consuming, and still, there may be a chance of remaining the problem. In that case, you should go for an automated tool like LMbyte OST to PST Converter.

This software helps you to repair your inaccessible OST file. Further, you can save that file into different extensions. Follow these steps to fix the error through this software:

  • Install and launch the software.
  • Now search for OST file through browse option.
  • Operate the process by choosing the convert option.
  • First, the program will scan the OST file and then convert it to the PST file.
  • After conversion, you can see the preview.
  • Now, verify if all data are the same or not.
  • Click on the save button to restore recovered data.
  • You are all set, now you can easily access the file through any outlook profile.


The outlook is the most professional email program. Thus, problems related to it can easily be solved through a few steps as we mentioned above. We hope all those methods will be helpful to you while fixing “OST file cannot be opened error”.