OST File Not Recognized By Outlook 2016 / 2013 / 2010 – [Solved]

OST file not recognized by Outlook

Outlook creates both OST and PST file formats. An OST file plays an important role when users need to work offline in Outlook. That means, if there is no Exchange Server connectivity or slow internet connection, the OST file allows you to work. Once the connection with Exchange Server establishes, the OST file is updated in the Exchange Server automatically. However, there is a chance that OST files may get corrupted or damaged, which gives an error message “OST file not recognized by Outlook”.

Troubleshoot “OST File Not Recognized by Outlook” Error Message

this situation, people need a solution to get rid of this problem. But, it is not so easy to find a reliable and suitable technique. Hence, in the upcoming section of this blog, we are going to talk about the appropriate methods to fix the OST file not recognized by Outlook and cannot open an error message.

When users try to open the Outlook application, they will get different types of error messages. All error messages encounter when an OST file is not recognized by Outlook.

  • 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.
  • The outlook data file cannot be accessed.

Why Users Get OST File Not Recognized by Outlook Error Message?

There are mainly two reasons that will cause the OST files cannot recognize by the Microsoft Outlook error message. Both are discussed here:

  • Microsoft Outlook is not able to recognize the OST file if your OST file is corrupted or damaged due to any reasons.
  • If Microsoft Outlook is unable to access the associated Exchange mailbox or not able to synchronize the mailbox with offline folders in the OST file due to any reason. Then users will get the OST related errors like “OST cannot recognize by Outlook”.

What to Do When OST File Not Recognized by Outlook?

When the OST files cannot recognize by Microsoft Outlook and encounters various errors, you need to fix this problem by following these steps:

  1. First of all, exit Outlook application, go to the Control Panel and click on the Mail button.
  2. In the Mail Setup dialogue box, click on the Show Profiles. Then, choose your profile name and select the Properties option.
  3. Go to the E-mail tab and select the Exchange account.
  4. After that, click on the Change button & enable the Use Cached Exchange Mode option.
  5. Go to the More Settings >> Advanced tab and select the Offline Folder File Settings option.
  6. In this step, choose the Disable Offline Use option then just click on “Yes” to process further.
  7. Again go to Offline Folder File Settings, select OK and Yes.
  8. Now, under the Cached Exchange Mode Settings, mark the checkbox corresponding to the Use Cached Exchange Mode option.
  9. Click on the OK button >> Next then hit on the Finish button.
  10. Finally, close the Account Settings and Mail Setup wizard.

After performing these steps, you will surely fix the error message OST file is not recognized by Outlook 2016 / 2013 / 2010. But, there are some situations where users are still unable to fix this OST file issue even after performing the manual method. In this case, it is better to opt for a reliable third-party tool like OST to PST Software.

This tool is capable enough to recover all types of corruption in the OST file that can easily resolve the OST file is not recognized by Outlook error. This software can easily decrypt S/MIME and OpenPGP encryption. For more info, the user can try the demo version of this utility.

Steps to Resolve OST File Error with SysTools OST Recovery Tool

  1. First of all, download, install and run the application on your machine.
  2. Now, you can preview the OST files along with their attachments.
  3. After that, you have an option to export the OST file into your desired file format.
  4. Finally, the corrupted OST file will be recovered successfully.

Wrapping Up

In this blog, we have discussed a problem “OST file is not recognized by Outlook”. This error message occurs due to many reasons. There are both manual and third-party solution is given to fix the error message. But, manually it is difficult to recover the corrupted OST files. Hence, OST to PST software is suggested to use by the technical experts.

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