Outlook Fails to Open on Windows

Summary

This article describes how to resolves issues opening Microsoft Outlook on a Windows machine.

Body

Overview

This article describes how to resolves issues opening Microsoft Outlook on a Windows machine.

Environment

Microsoft Outlook in Windows

Troubleshooting/Resolution

For this particular issue, the Outlook data file needs to be re-created.  You can do that with these steps:

Open Outlook and make note of the file path and file name listed at the top of the Inbox Repair Tool window (Usually something like: C:/Users/eID/AppData/Local/Microsoft/Outlook/eID@jmu.edu.ost)

  1. Close Inbox Repair Tool and all Outlook windows
  2. Open File Explorer
  3. Select View in ribbon at the top, go to the far right, and check boxes next to File name extensions and Hidden items
  4. Navigate to file path noted in step 1
  5. Right-click on data file (Usually eID@jmu.edu.ost) and choose Rename
  6. Add .old after .ost and confirm change
  7. This file will be recreated as soon as you open Outlook but should preserve your added accounts and preferences
  8. Open Outlook normally and close File Explorer once it opens
Additional Information or Notes

If you still get the same error message, be sure you have renamed the correct data file (.ost file) that is causing the issue. The problematic file can have a personal JMU email address in its name, or a shared mailbox name, or an internet calendar listed.

For additional questions you can contact the JMU IT Help Desk at helpdesk@jmu.edu or 548-568-3555.

Details

Details

Article ID: 20286
Created
Thu 9/4/25 3:52 PM
Modified
Tue 10/28/25 1:07 PM