Last reviewed on July 22, 2014   —  36 Comments

We're seeing reports that Outlook won't open, returning a (basically useless!) error message that Outlook won't open. Attempting to open the Mail applet in the Control panel results in an error message that Outlook is out of memory or system resources.

"You need more memory or system resources. Please close some Windows and try again."

To get Outlook back into working mode, open the registry editor and delete or rename the windows messaging subsystem key. We don't know why the key is corrupt, but this seems to fix the problem and doesn't take as much effort as completely removing Office and reinstalling.

Renaming this key means you will lose your profile and will need to recreate it. There really is no way to avoid this. Sorry.

Outlook 2010 and older:

HKEY_CURRENT_USER\Software\Microsoft\Windows NT\CurrentVersion\Windows Messaging Subsystem

Outlook 2013:


Edit the Registry

  1. Press Windows key + R to open the Run command.
  2. The renamed registry keyType regedit in the Open field and click OK.
  3. Locate the key then right click on it and choose Rename.
  4. Type OLD at the end of the name.
  5. Try opening the Mail applet to create a new profile.

If Outlook works, you can delete the renamed key.

<Use the registry editor to rename the key

In Outlook 2013, the key is at HKEY_CURRENT_USER\Software\Microsoft\Office\15.0\Outlook\Profiles
Outlook 2013's profile key


  1. Leonard says

    Nice post which the registry editor and delete or rename the windows messaging subsystem key. We don't know why the key is corrupt, but this seems to fix the problem and doesn't take as much effort as completely removing Office and re-installing. Thanks a lot for posting.

  2. Steve says

    I reinstalled office enterprise 2007 twice and neither the mail applet or outlook 2007 would work. After spending 24hours of my work week on finding an answer your post was equivalent to a miracle!

  3. Robert says

    I'm having this same issue but when I look for the Windows Messaging Subsystem its not there. Outlook 2013. I am horribly baffled by this. I called Microsoft support and they couldn't figure out the problem... Help

    • Diane Poremsky says

      The profile path moved in Outlook 2013. It's under the office path.
      HKEY_CURRENT_USER\Software\Microsoft\Office\15.0\Outlook\Profiles - rename Profiles to Profilesold then restart Outlook and make a new profile.

  4. Robert says

    I tried that and i get the same thing. I rebooted the pc to see if that would and the same thing. I signed in as a new user with admin rights and the same for that user. I noticed under profiles in the registry there wasnt any other folders under it. I looked on another pc running outlook 2013 and the was several folders under profile. Still stumped. A microsoft engineer is supposed to contact me today. I will reply back if he resolves the issue.

    • Diane Poremsky says

      If you upgraded from an older version of Outlook, the Windows Messaging Subsystem key will be present, leftover from the older version. Outlook 2013 copied the profile to the new location.

      So the only problem you are having is Outlook crashes and Control Panel, Mail won't open? Did it ever work correctly?

  5. Robert says

    This is a new PC with a new installation of Office 2013 that was done this past Saturday. Outlook 2013 initially opened after installation. I was able to setup Outlook and connect to our Exchange 2010 email server. I rebooted the system several times after that. Outlook still opened without a problem. My user went to use it on Monday morning and this was the message he received.

  6. Robert says

    I've tried outlook.exe /resetnavpane that didn't work and I checked the compatibility mode and that's fine. That's why I'm baffled. I've spent 2 days so far researching this problem and nothing worked. I even tried uninstalling and reinstalling the program. And still nothing. I even downloaded another copy of the program and still the same thing. This will be one to document.

    • Diane Poremsky says

      It's probably going to be something goofy only someone in front of the computer can figure out. :( Have you tried Safe mode?

  7. Robert says

    Are you talking about booting the system in safe mode and trying it? if so, No because I have not been onsite since the installation. I have been troubleshooting remotely. Trying to start Outlook in safe mode doesn't work either if that's what you meant.

    • Diane Poremsky says

      Outlook in Safe mode was what I wanted to know. Did you use Easy Transfer or anything to copy settings from the old computer? I've heard of problems like this with Outlook 2010 and 2013 installed on the same machine and it became worse after the last round of updates. The guy had to uninstall Outlook 2010 to make it work. But if this is a clean machine with only Office 2013, that is not the problem.

      Were any updates installed between when it worked and when it didn't?

  8. Robert says

    This is a fresh clean machine out of the box. No previous use. As for updates installed afterwards. There was a couple of Windows updates but No Office updates. and after the updates was installed I still was able to open Outlook.

    • Diane Poremsky says

      I'm at a loss for ideas - it'll probably turn out to be something stupid.

      I'd probably try renaming the two Outlook folders - %appdata%\microsoft\outlook and %localappdata%\microsoft\outlook - and repair office. See if outlook works. If so, one of the support files could be corrupt.

  9. Robert says

    Im on the phone with microsoft level 2 support. He deleted all outlook folders in the registry and now we are waiting for the online repair to finish. I downloaded the iso file but no he insisted to wait 1 hour for this online repair. I will let you know if this was a waste of time

  10. Robert says

    Well it fixed the problem for my admin profile but the users profile is still broken. So now i have to sit here for another hour to repair the users profile. He says we cant use the software i downloaded earlier that would save us time. But have to do a online repair. I will post back in an hour to let you know if that worked.

  11. Robert says

    Update after 4.5 hours of working on this with Microsoft (2 hours wasted on online repairing) , the problem still exists. Now at least I'm able to access the Mail program under Control Panel and create a new profile. But now I get a message that the information store in not accessible? WTH.. Microsoft tech was horrible. Would not respond to the chat, would not call me on the phone. I gave up on this and had to cut him off from my PC. Now I will resort to wiping the PC and starting from scratch using the software I downloaded instead of the ClicktoRun crap or go to Office 2010. Oh yeah the tech did say this is a known bug in Office 2013. Well Microsoft needs to fix it... I'm done for the night sorry for the rant but it's been 3 days of hell dealing with this issue and its going on 4 days.

    • Diane Poremsky says

      I don't think its a known or common bug but will check with my support contact. Unless you have a volume license (or technet/msdn), everything is click to run. It doesn't compare at all to the Office 2010 Click to run software though.

  12. Robert says

    Ok, I didn't want to leave this post open. So, here is what "I" did to get this thing working. I uninstalled Office 2013, Ran CCleaner to cleanup the Registries, Deleted All Microsoft Office folders, Deleted the user profile (Which Microsoft told me not to do) said a little prayer.. Rebooted the system. Reinstalled Office 2013 product I downloaded from Microsoft. Recreated the users profile and everything worked. Rebooted the system 5 times and opened Outlook, Word and Excel successfully. Thanks for all your help also.

  13. Yatin S. says

    Thanks a ton!! I had wasted 10 hours without any gain, un-installed office, re-installed.. tried every possible way I could do, but it was not ready to start.. Fortunately came across this note and it worked!! problem solved... Great Diane Poremsky :)

  14. Walt says

    Thanks for this post. It fixed a problem I was having with trying to open a reinstall of Outlook 365 (2013). I had uninstalled a home copy of Office 365 from this computer and then needed to reinstall for a time. I wanted to add my work Exchange account to this installation on this machine for my use at work (I usually work at home).

    When I opened Outlook it was looking for a deleted .PST file and wouldn't allow me to setup a new account.

    I was stymied and so has Microsoft Support been useless. Five calls so far today with disconnects and transfers and even a LogMeIn session with Microsoft didn't help. I was supposed to be transferred to advanced help on two occasions, only to be disconnected. Very frustrated.

    Found this thread, tried the solution, and low and behold, when I restarted Outlook it asked me to add a profile. I did, and it is working just fine. So this is a solution to this particular problem also.



  15. MR says

    MS may not be admitting there is an issue but try searching for it - lots of forum entries chatting about it. The fix is inconsistent, some fixed by a repair, some by the registry delete, some by reinstall. None of these have fixed my failing system and as many have noted in various forums, I'm not alone. I'm attempting the MS forced uninstaller next -

  16. Clay says

    This problem is happening on about 8 out of every 10 computers I'm setting up on our domain. Does anybody know what I'm doing wrong? There are times I've had to do this three times in a row before Outlook stopped destroying itself. For me it seems like Outlook will run fine until I go to the Options screen, then it will crash and never open again until I perform all these steps.

    • Diane PoremskyDiane Poremsky says

      What version of Outlook and which OS? Did it start recently, such as right after updates were installed?

  17. Chloe says

    This worked great to redo what I messed up setting up Outlook. But now its telling me that Microsoft Exchange has to be online or connected to complete this action. Any suggestions?

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