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Best Three Methods to Fix Hotmail.ost is Not an Outlook Data File Error

This blog is mainly posted to provide effective solutions to fix very common errors “Hotmail.ost is not an Outlook data file“ of Microsoft Outlook. But direct discussing solutions will be incomplete information. So I am going to tell some basic informations before introducing solutions to fix “Hotmail.ost cannot accessed” error.

When you configure a Hotmail account in MS Outlook that time an additional plugin “Microsoft Outlook Hotmail Connector” is required. Once you configure a Hotmail account, MS outlook creates an .ost file to save emails, contacts, notes and calendar items etc. The user can use this OST file to read items even when internet connection is not available.

Why Microsoft Outlook Produces Hotmail.ost is not an Outlook data file Error?

The OST files created by MS Outlook for Hotmail account works fine until you don’t delete profile or uninstall MS Outlook. But when you reinstall Microsoft Outlook or delete your profile that time OST file gets inaccessible and produces very common errors such as:

  • ost is not an outlook data file
  • ost is not an offline folder
  • ost cannot be accessed
  • ost cannot be opened

Method: 1- Fix Error hotmail.ost is not an outlook data file

This method is very helpful to get rid from Hotmail.ost is not an offline folder or Hotmail.ost cannot be opened. So just follow the steps:

  1. In the very first step, delete the Hotmail account.
  2. Uninstall the Outlook Hotmail Connector and Close Outlook..
  3. Delete the OST file created by MS Outlook.
  4. Now reinstall the Outlook Hotmail Connector.
  5. Configure same Hotmail account with a new profile and Outlook will create a new OST file.

Method: 2- Fix Error Hotmail.ost is not an offline folder

This is another good solution already suggested by many Microsoft MVPs for the same query. So Check if Outlook is running in compatibility mode. Follow the steps:

  1. Go to Computer >> C Drive >> Program Files. (For 64bit OS: Program Files (x86))
  2. Go Microsoft Office >> Office 14.
  3. Right click on Outlook.exe (application) >> properties.
  4. Under Compatibility tab >> uncheck the compatibility mode >> OK.

Method: 3 Fix Error Hotmail.ost is not an Outlook data file by converting file to pst format

If the above both methods do not help, then go with this most effective method. By using this reliable method you can fix these errors and access all precious mail with Outlook 2016, 2013, 2010 and 2007 etc.

  1. Download and install free demo of the tool:
  2. Add an OST file which you want to convert. The tool will load and preview all items.
  3. Click on the Export button, choose reliable options and finally click Export


You can examine these three methods to fix Outlook errors like: Hotmail.ost is not an Outlook data file or Hotmail.ost cannot be opened. The last method is very powerful and works in all conditions even if OST file is corrupted or orphaned. So I will recommend you to use this simple method to regain data from inaccessible OST files. You can also check how to import/open PST file in MS Outlook in another post.

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