Known Issue: Unable to launch Outlook (.ost in use and cannot be accessed)

When you attempt to launch Outlook, an error message is displayed on the screen that says "The file C:\Users\userid\AppData\LocalMicrosoft\Outlook\ is in use and cannot be accessed. Close any applications that is using this file, and then try again. You may need to restart your computer." and Outlook fails to start. Rebooting your computer does not resolve the issue.

This is caused by the corruption of Outlook's profile file. You will need to reset your Outlook following instructions included in the Related Articles section on the right. If you had any shared mailboxes included in your Outlook, you will need to add them there again after resetting Outlook. See Related Articles section on the right.

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Article ID: 58432
Fri 7/27/18 3:57 PM
Mon 10/4/21 1:14 PM

Related Articles (1)

This article explains how to reset Outlook profile which stores your e-mail account data.