Microsoft Outlook 2013 crashed on me today. When I tried to launch it again, I received an error that said:
Outlook Data File – The file C:\Users\user name\AppData\Local\Microsoft\user name\username.ost is in use and cannot be accessed. Close any application that is using this file, and then try again. You might need to restart your computer.
Restarting my computer was not an option at the time. Here’s how you can solve the issue.
Fix 1 – Kill All Outlook Related Processes
- Right-click the task bar and select “Task Manager“, or press CTRL + ALT + Delete, then choose “Task Manager“.
- Select the “Processes” tab.
- Look for anything named “Communicator“, “Lync“, “ucmapi” or “Outlook“. If you find any items related to these, select it, then select the “End task” button.
Fix 2 – Disable Cached Exchange Mode
- Close Outlook.
- Open “Control Panel” and select “Mail“.
- Select the “Email Accounts” button.
- Choose the “Email” tab.
- Highlight the email address giving you the warning (email.ost), then select “Change“.
- Uncheck “Use Cached Exchanged Mode“.
- Select “Next” then “Finish“.
Now attempt to launch Outlook again. Hopefully, it works fine now.
If neither of these work, you might have another computer or program grabbing the OST file. Makes sure anything that uses Outlook is completely closed on any workstation that may interface with Outlook.
Thanks to Alix Jimenez for Fix 2.
yopa says
Lifesaver! thanks for the great documenting.
Trisha Perez says
Thank you so much! Fix 2 worked for me on Outlook 2016.
Cecile says
The fix works!
ailsa says
thank you!
Jacky.Yin says
good job and thanks the document for the issue!
kim says
solved my issue. thank you!
Florisz says
Thank you! Fix 1 did it for me; End task of ‘Skype for business (32 bit)’ under Processes and “ucmapi”(also part of Skype for business) under ‘Details’ tab.
vani says
thank you so much :)
pramod patil says
Thank you. #1 fixed my issue.
Sid says
Thank you. #1 fixed my issue.
Sathish Kumar says
Thank You , Fix 2,,, worked for me.. :)
rax says
The #2 worked for me. Awesome!!
Del says
Thank you! #2 Was the solution for me. Since a couple of months Outlook and Skype for Business (Lync) kept fighting for my .ost file. Now everything works. 🍻
Krishna Cheedella says
Thank you very much. Have a great day.
Suzanne says
Thank you. #1 fixed my issue.