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Bug: Only one version of Outlook can run at a time

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› Outlook › Bug: Only one version of Outlook can run at a time

Last reviewed on July 17, 2018     13 Comments

Applies to: Outlook (classic)

The problem: If Outlook is running and you click the taskbar icon, instead of another Outlook window opening, an error message comes up, telling you that Outlook is having trouble starting and you can only run one version of Outlook at a time.

Sorry, we’re having trouble starting Outlook. Only one version of Outlook can run at a time. Check to see if another version of Outlook is running or try restarting your computer.

Users with Insider builds have had this message for several weeks and it’s just now rolling out in the current releases (Version 1806 Build 10228.20080).

The error message is annoying and pointless, as a second Outlook window opens after you click OK to dismiss the dialog.
outlook error message

The only way to stop it (until Microsoft fixes it) is to either add the /Recycle switch to the Outlook shortcut, or use the /select outlook:foldername switch if you want to open additional windows.

  1. Open File Explorer and browse to C:\​ProgramData\​Microsoft\​Windows\​Start Menu\​Programs.
  2. Right click on the Outlook Shortcut and choose Properties.
  3. Add /recycle to the Target path is you want to reuse the window. "C:\​Program Files (x86)\​Microsoft Office\​root\​Office16\​OUTLOOK.EXE" /recycle
  4. Add /select outlook:inbox to the Target path is you want to open a new window: "C:\​Program Files (x86)\​Microsoft Office\​root\​Office16\​OUTLOOK.EXE" /select outlook:inbox
  5. Save and close the properties dialog.

Repeat with the Outlook shortcut at C:\​Users\​%username%\​AppData\​Roaming\​Microsoft\​Internet Explorer\​Quick Launch\​User Pinned\​TaskBar

After you make this change, when you click on the pinned taskbar icon or the start menu shortcut, either the open Outlook window will come into focus, without opening additional windows or displaying an annoying dialog or, if using the Select switch, a new window will open.

Bug: Only one version of Outlook can run at a time was last modified: July 17th, 2018 by Diane Poremsky

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About Diane Poremsky

A Microsoft Outlook Most Valuable Professional (MVP) since 1999, Diane is the author of several books, including Outlook 2013 Absolute Beginners Book. She also created video training CDs and online training classes for Microsoft Outlook. You can find her helping people online in Outlook Forums as well as in the Microsoft Answers and TechNet forums.

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vamshi krishna
August 17, 2020 2:42 am

Still i am unable to solve the solution

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Tim
March 31, 2020 1:28 pm

Hi, The "Sorry, we’re having trouble starting Outlook. Only one version of Outlook can run at a time. Check to see if another version of Outlook is running or try restarting your computer." appears whenever I click on the Outlook "new mail" notification that appears for 10 seconds or so in the bottom right of the desktop. I don't pin any applications to the task bar, so I'm not sure that the stated solution would apply. Current environment is: Windows 10 Home, Version 1903 (OS Build 18362.720) Microsoft Office 365 ProPlus - en-us, 16.0.11929.20648 One mail profile with two accounts: Outlook personal account (free version) Outlook business exchange account (from employer) This was occurring on Office 2016 and then when I unwillingly upgraded to Microsoft Office 365 ProPlus, the issue stop occurring for one Outlook session. It started again the following day when I opened Outlook and continues to occur. I have a suspicion that it may have something to do with the two Outlook mail accounts, but not sure what else to try? As part of the employer provided Microsoft Office 365 ProPlus package, Skype for Business also has an occasional error message about not being linked to my… Read more »

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Zoltan
Reply to  Tim
April 28, 2021 9:15 am

"appears whenever I click on the Outlook "new mail" notification that appears for 10 seconds or so in the bottom right of the desktop."

I also get this message under exactly the same circumstance, and it only started recently for some reason!

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Samantha Khandoo
March 10, 2020 8:42 am

Thank you your solution was right on the button!

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ariel sa
February 27, 2020 8:41 pm

hit change and then repair on office product through controll panel/programs and features

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Sandip Parmar
February 25, 2019 12:48 pm

Thank you for the quick turnaround, the /select outlook:inbox is exactly what I am looking for!
I have applied to outlook properties and issue is resolved.

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Erich
August 28, 2018 10:11 am

Was seeing this only when opening Outlook, if I inadvertently clicked on the Outlook icon on the task bar twice, I would get that error. Just tried to open a new Outlook instance while another was already open, as well as by attempting to open a 2nd instance while the first was opening and the issue is not now occurring (Windows 7 x64 Enterprise Version6.1.7601, running O365 2016 Version 1807 (Build 10325.20118). Not sure if the issue was resolved in the 8/14 release or in the 7/17 release

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Jarod Hottel
August 3, 2018 1:55 pm

You just saved me from a mental break down. Thank you.

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Mark Vdovydtchenko
August 3, 2018 11:35 am

Thank you Diane, we just rolled out Office 365 updates and didn't catch this bug until some of our users brought it up. Hopefully the next minor update fixes this bug.

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