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.

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.

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

What data file types does Outlook support? While working with Outlook, you will encounter two data file types: OST and PST. OST (Offline Storage Table) file types allow you to work offline.

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 ...

A File Cannot Be Opened in Microsoft Office Outlook. If you cannot open Microsoft Outlook for some reason, it can make communicating with employees, clients or suppliers rather difficult in some ...

The biggest caveat in opening OLM files in Windows Outlook is that OLM file cannot be accessed in Windows platform. This is because Outlook for Windows only supports PST file format.

If the Outlook Express data file cannot be accessed, whether you can still get at your emails depends upon how you had Outlook Express configured.