Solution for OST File Not Recognized by Outlook Error

OST file plays a major role when the user wants to work offline in Outlook (when there is no connectivity with Exchange server). OST file allows users to work on Outlook during slow internet connectivity or when the internet connection is lost. Later, once the connection with Exchange server establishes, this OST file is automatically updated in the user’s Exchange account.

But, sometimes unexpected errors like “OST file not recognized by Outlook” is thrown by OST file will put the user in trouble. At times, when you start Outlook, you will get the different kinds of error messages like:

Cannot open your default email folder. The file C:\Users\ME\AppData\Local\Microsoft\Outlook\ME.OST is not an Outlook data file (.ost)

Cannot open your default email folder. The file xxx.ost is not an offline folder file.

Outlook data file cannot be accessed.

Above listed are the various forms of OST file not recognized by Outlook error.

Mainly there are two reasons that will cause the above kind of OST error messages:

How to Fix OST File Not Recognized by Outlook Error?

Follow these steps to resolve OST file not recognized by Outlook.

Step 1: Exit Outlook, go to Control Panel and click on the Mail button.

Step 2: In Mail Setup dialogue box, click on Show Profiles, select your profile name and choose Properties.

Step 3: On E-mail tab select Exchange account, click on the Change button and enable Use Cached Exchange Mode.

Step 4: Go to More Settings. On the Advanced tab, select Offline Folder File Settings.

Step 5: Select Disable Offline Use option then, click on “Yes”.

Step 6: Again go to Offline Folder File Settings, select OK and Yes.

Step 7: Under Cached Exchange Mode Settings, tick the checkbox Use Cached Exchange Mode.

Step 8: Click on the OK button, go Next and Finish.

Step 9: Close the Account Settings and Mail Setup wizard.

In case, even after trying above resolution you are unable to fix OST file not recognized by Outlook error, then use reliable OST to PST Converter software in order to fix this problem. To get effective result use Yodot OST to PST Converter tool.

Software to Convert When OST File Not Recognized by Outlook:

Yodot OST to PST Converter software is the reliable method to convert when OST file not recognized by Outlook on Windows system. This program can easily recover important emails and other data from corrupted or damaged OST file. Along with repairing damaged OST file, it will guide you to easily convert OST file to PST format. It can also assist you to restore attachments, sent items, notes, calendars, rules, alerts, etc. from the OST file that is not recognized by Outlook by changing it to PST file.

In addition to OST file not recognized by Outlook error, it can also assist you in solving other Outlook error messages like OST is already in use by maximum number of applications, Exchange error object could not be found, OST file is in use cannot be accessed, unable to expand folder of OST file, and even Microsoft Exchange errors in background synchronization. This utility is compatible to repair OST files on all versions of Windows operating system such as Windows 10, Windows 8.1, Windows 8, Windows 7, Windows XP, Windows Vista, Windows Server 2003 and 2008. This application will be handy to recover Outlook data that is lost or deleted from your corrupted file as well.

This powerful program is compatible with all versions of Microsoft Office Outlook like Outlook 2016, Outlook 2013, Outlook 2010, 2007, 2003 and 2000.

Steps to Fix OST File Not Recognized by Outlook Error with Yodot:

Step 1: Launch Yodot OST to PST Converter software and click on the Open OST File button (use Find OST File option if you don't know the OST file locations).

Step 2: Next, browse and select the OST file that you want to convert into PST format.

Step 3: Mention destination location where converted PST file has to be saved and click on the Convert button.

After the OST to PST conversion process, the tool will display a confirmation message OST file conversion completed.


  • Make sure that you have configured OST file properly
  • Ensure proper internet connectivity before synchronizing your OST file

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