Creating new Outlook profile or rebooting the computer fixes the issue. I tried to manually access the OST file location and I could read the file just fine. Create a new dummy PST using the same Account Settings window and Data Files tab. Add a new PST file - wherever you like (you won't be keeping it). If you think a third-party add-in might be causing the error, try starting Outlook in Safe mode without any add-ins or extensions loaded to see if it works. When you want to replicate a copy on ...