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Outlook 2010: How To Fix Error Cannot Start Outlook or Open the Outlook Window

This morning while working on my PC, my Outlook 2010 client crashed and refused to re-open. When restarting Outlook it would continually crash displaying the same error messages repeatedly. Here’s how I fixed it.

First the error messages:

“Microsoft Outlook exited without properly closing your Outlook Data file: FILE.OST. Microsoft Outlook must be restarted. If this error message recurs, contact support for Microsoft Outlook for assistance.”

“Microsoft Outlook exited without properly closing your Outlook Data file: FILE.OST. Microsoft Outlook must be restarted. If this error message recurs, contact support for Microsoft Outlook for assistance.”

After clicking OK, the following error message appears:

“Cannot start Microsoft Outlook. Cannot open the Outlook window. The set of folders cannot be opened.”

“Cannot start Microsoft Outlook. Cannot open the Outlook window. The set of folders cannot be opened.”

Each time Outlook is opened, the same two errors above display and Outlook will not open.

To resolve the issue, navigate to your Windows Taskbar and find the Microsoft LYNC or OCS chat Client.

find lync chat client on windows task bar

Right click the Microsoft LYNC or OCS chat client and click Exit

Exit lync chat client

Outlook should now open without any issues.

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43 Responses to Outlook 2010: How To Fix Error Cannot Start Outlook or Open the Outlook Window

  1. Quintus January 24, 2012 at 6:50 am #

    Thank you for yet another great article. This blog has learned a me a lot of usefull stuff.

    I do have a question:
    ” Right click the Microsoft LYNC or OCS chat client and click Exit”
    What does Microsoft LYNC and OCS chat client has to do with this error? The solution is working perfectly I just don’t understand Why it’s working.

    • Quintus January 24, 2012 at 6:52 am #

      Teached* Teached not learned. Sorry!

      • bystander October 25, 2013 at 9:47 am #

        taught. Strike two.

  2. T.Johnson Miller February 4, 2012 at 10:44 am #

    “Outlook.exe /resetnavpane” worked for me. Thanks.

    • Steve Krause February 6, 2012 at 6:44 pm #

      Great tip. Will need to test htis out. Thnx Miller.

      • bojan December 10, 2012 at 12:00 am #

        i got this error very often, so i shall check this and report if solved permanently.

  3. Ali March 21, 2012 at 9:48 am #

    Great tip. Thanks a lot for your support.

  4. Jmatch83 April 11, 2012 at 8:15 am #

    Thanks for the post Steve, this worked.

    @Quintus: this is probably because Lync and Outlook share information (like the .ost file), if Outlook didn’t properly dispose of it’s handle to the file and Lync still has an open connection, then Outlook cannot initiate a handle to the file when you start it up. When Lync is closed, all handles to the file would be closed and the file would be unlocked, ready for another handle.

  5. Jimmy April 26, 2012 at 1:39 pm #

    Wow! Spent some time on this one….thanks for the fix!

  6. Peter May 27, 2012 at 7:06 pm #

    Hi i do not find the Microsoft LYNC or OCS chat Client. on the task bar. I am suffering from this problem from very long time though outlook resume after restarting. Can you suggest me if there is other way to fix this problem ?

  7. ost2pst May 30, 2012 at 4:31 am #

    SysTools OST Recovery

    • Kip June 15, 2012 at 12:19 pm #

      Okay, so where do we find SysTools OST Recovery?

      Thanks bunches!

  8. Kip June 15, 2012 at 12:22 pm #

    Never mind! Found it! Thanks!

  9. ra June 20, 2012 at 1:37 am #

    that was incredibly useful, first time i discovered this problem, thank you for the tip.

    • Steve Krause June 20, 2012 at 7:22 am #

      Glad we could help and welcome to my site!

  10. Anthony August 20, 2012 at 5:31 am #

    That was extremely useful. Thank you!

    • Steve Krause August 21, 2012 at 9:18 am #

      No problem. Welcome to the site!

      Sent from my Mobile

  11. girish doshi August 21, 2012 at 1:20 am #

    This was helpful, quick one thanks a ton Steve.

  12. Mike September 10, 2012 at 8:02 am #

    thanks so much for the help! I always forget how much Lync and Outlook are so co-dependent.

  13. Ben Northway November 27, 2012 at 6:52 am #

    Cisco Jabber seems to have been the culprit for me. Closing Jabber allowed Outlook 2010 to open. Thanks for the tip!

  14. bojan December 9, 2012 at 11:59 pm #

    and this is not a solution because i dont want to close lync every time it happens.
    is there any permanetnt solution?

  15. Adam Griffin January 23, 2013 at 4:00 pm #

    like a charm. brilliant.

  16. Fernando March 7, 2013 at 9:35 am #

    Thank you!

  17. Gaga April 3, 2013 at 9:41 am #

    Hi,

    It worked .

    I do not know what is the connection b/w both , but it really worked

    thanks !!

  18. Dorian Earl April 10, 2013 at 3:33 am #

    Yes ! It worked very Fine for my Outlook, but I have some more great tool for this troubled of ms outlook, try Kernel for PST repair tool to 2013 (both 32 bit and 64 bit), 2010, 2007, 2003, XP, 2000 and 97 versions of Personal Storage Table documents. Scanpst tool recovers entire Personal Storage Table items including emails, drafts, calendars, journal, notes, tasks, contacts etc.

  19. CJ April 17, 2013 at 7:15 am #

    Awesome Your the best i got an applause from office after fixing my leads system

  20. Staci April 21, 2013 at 6:56 am #

    Thank you so much! What an easy fix!!

  21. Edeh Daniel April 23, 2013 at 1:32 am #

    How do I find the Microsoft lync on my window 7 computer.I have check my taskbar but cant find anything as such.please I need help.

  22. neeraj May 2, 2013 at 11:14 pm #

    This worked for me as well…also…we don’t use the usual office communicator but a customized communicator along with my outlook.
    i signed off and restarted Outlook, Bingo!

  23. Riccardo Moschetti June 25, 2013 at 6:37 am #

    Well this was some help…
    Thanks Steve!

  24. haj October 24, 2013 at 3:05 am #

    Thanks Steve,

  25. deepak s February 9, 2014 at 8:17 pm #

    Worked like magic for me .
    Such simple things cause such a big mess

  26. gowrisankar April 20, 2015 at 11:43 pm #

    Thanks Steve,

  27. Ankita June 10, 2015 at 3:27 am #

    Restarting lync helps.. Thanks Steve.

  28. Ravindra July 16, 2015 at 2:54 am #

    thank you very much this is working

  29. vaishnav August 23, 2015 at 5:37 pm #

    Great it helped!

  30. rsolanki November 19, 2015 at 5:54 am #

    This worked for me as well

  31. Esther December 2, 2015 at 9:32 am #

    My culprit was Cisco Jabber. It seems like it can be any chat client that connects to your email to display your calendar appointments and meetings. Makes sense now but it wouldn’t have dawned on me on my own. Thanks! 🙂

  32. Subramani M June 16, 2016 at 2:32 am #

    Its very helpful Thank You

  33. satheesh August 1, 2016 at 6:55 am #

    Thank you so much….really helped me a lot

  34. Peter Larsen August 16, 2016 at 10:47 pm #

    That is cool – it worked 🙂

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