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.

Microsoft Office Outlook maintains everything in a data file, also called PST or OST file. It is an offline copy of mailbox data stored on a local PC. In case of issues, you must delete the data ...

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 ...

I then deleted the default Outlook folder, whatever that was called at the time.<P>I am now looking to re-backup my outlook files, and cannot find a new .pst on my computer to copy.

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.