Outlook Data File – The file C:\Users\<username>\AppData\Local\Microsoft\<username>\username.ost is in use and cannot be accessed. Close any application that is using this file, and then try again.

Fix Cannot open Outlook window. The file .ost cannot be accessed, You must connect to Microsoft Exchange before you can use Outlook data file.

Check where each of your email accounts is delivering mail. After migration to Outlook 2010, sometimes the location is missing. You can check it from here: Click File/Account Settings.

Your notebook powers on perfectly and you open up Outlook only to see “Outlook data file cannot be accessed”. The colour drains from your face and the words “oh no” escape your lips in a ...