"Outlook Not Responding" error - solutions for hanging, freezing and crashing problems

This article explains how to resolve problems with Microsoft Outlook hanging, freezing or crashing. Our 9 working solutions will help you fix the "Outlook Not Responding" issue and bring your Outlook back to life. The solutions work for Outlook 365, 2021, 2019, 2016, 2013, and earlier versions.

Has it happened to you that you work with Microsoft Outlook as usual, click on a message to read or reply to it, or take some other action you performed hundreds of times in the past, and all of a sudden Outlook won't open and not responding?

Microsoft Outlook not responding

In this article I will show you easy solutions, tested on my own experience (and working!), to fix issues with Outlook hanging, freezing or crashing. We'll start with very basic steps that address the most obvious reasons why Outlook stops working:

Remove hanging Outlook processes

From time to time Microsoft Outlook adopts quite an annoying habit to hang around even if the user persistently attempts to shut it down. Technically, it means that one or more outlook.exe processes would stay in memory preventing the Outlook application from closing correctly and not letting us, users, start a new Outlook instance. This problem existed in earlier versions and it may occur with recent Outlook 2013 and 2010.

The first thing we need to do is kill all hanging Outlook processes. To do this, start up the Windows Task Manager either by pressing Ctrl + Alt + Del, or by right clicking the taskbar and choosing "Start Task Manager". Then switch to the Processes tab and find all OUTLOOK.EXE items in the list. Click on each OUTLOOK.EXE to select it and hit the "End Process" button.
Removing a hanging Outlook process

Start Outlook in Safe mode

When something goes wrong with Outlook, Microsoft recommends that we start it in Safe mode. What does it actually mean? Simply that Outlook will be loaded without your add-ins and customization files.

To start Outlook in Safe mode, click on its icon holding the Ctrl key, or enter outlook.exe /safe in the Run dialog box. You'll see a message asking you to confirm that you really want to start Outlook in Safe mode, click Yes.
Starting Outlook in Safe mode

Does this cure the problem? If it does and Outlook starts working properly, then most likely the problem is with one of your add-ins, which leads us to the next step.

Disable your Outlook add-ins

If the "Outlook Not Responding" issue did not cause you troubles in the past, it stands to reason to turn off the recently installed add-ins. I usually disable them one-by-one, closing Outlook with each change. This helps to pin down the culprit that causes Outlook to freeze.

In Outlook 2007, go to the Tools menu, click "Trust Center", then choose "Add-ins" and click Go.

In Outlook 2010 and Outlook 2013, switch to the File tab, click "Options", choose "Add-ins" and click Go.
Disabling Outlook add-ins

Now all you need to do is to untick the add-ins and close the dialog.

Close all open programs and applications

Outlook is one of the most complex applications of the Microsoft Office suite, which makes it extremely resource-hungry. Outlook may hang simply because it does not have enough memory to run or perform a required operation. This is often the case with outdated and low capacity PCs, however even modern and powerful ones cannot feel secured against this. Well, let's "feed" it by closing all other programs that you don't need at the moment.

Repair your Outlook data files

Use the Inbox repair tool (Scanpst.exe), which is included with Outlook installation, to scan your Outlook data files (.pst or .ost) and automatically repair damaged parts and errors, if any are found.

  1. Close Outlook, otherwise Inbox Repair won't start.
  2. Open Windows Explorer and navigate to this folder:
    • Outlook 2013: C:\Program Files (x86)\Microsoft Office\OFFICE15
    • Outlook 2016 and higher: C:\Program Files (x86)\Microsoft Office\OFFICE16
  3. Double-click Scanpst.exe to run the scan tool.
  4. Click "Browse" to select the .pst or .ost file you want to check.
  5. Open the "Options" dialog to choose the scan options.
  6. Click "Start" to begin the scan.
    1. If the Inbox repair tool spots any errors, it will prompt you to initiate the repair process to fix them.

Reduce the size of your mailbox and Outlook data file

As we discussed a few paragraphs above, Microsoft Outlook requires quite a lot of resources to be able to operate smoothly. And if your Outlook data file (.pst) or even one particular folder has largely grown in size, this might be yet another reason that makes Outlook irresponsive. There are 3 simple ways to cope with this problem:

  1. Keep your emails in several subfolders instead of one folder. If you store all your messages in a single folder (most typically Inbox), Outlook may not have enough time to display all those items while you are navigating to another folder or trying to open a certain email. And voilà - Outlook is hanging and we are angrily staring at the screen and agitatedly hitting the buttons, which only adds to the trouble. The solution is simple - create a few subfolders and put your emails to them, above all this will make your work a bit more comfortable
  2. Compact the Outlook data file. Know that simply deleting unneeded messages does not make the size of your .pst file smaller, nor does it recover the space on your hard drive. You need to specially tell Outlook to compact your data files. Before you do this, remember to empty the Deleted items folder so that Outlook can compress your data file.

    In Outlook 2010, you will find the Compact option on the File tab, under Info > Accounts Settings > Data Files tab. Choose your Personal folder and then click Settings. Go to the General tab and click Compact Now.

    Alternatively, in Outlook 2013 and 2010, you can right click the Personal folder (such as Outlook or Archive), then select Data File Properties > Advanced > Compact Now.
    Compact your Outlook data file.

    For other Outlook versions, please see Microsoft's instructions: How to compact PST and OST files.

  3. Archive your old items. One more way to reduce the size of your Outlook file is to archive older emails using the AutoArchive feature. If you need the detailed instructions, I'll refer you to Microsoft again: AutoArchive settings explained.

Let Outlook auto-archive or synchronize without interruption

Since we've started to talk about archiving, be aware that Outlook consumes even more resources than usually when it is archiving your emails or synchronizing messages and contacts with your mobile device, which results in a bigger response time. Don't push it and let it finish the job :) Usually, Outlook displays a special icon on its status bar or on the Windows system tray when auto-archiving or synchronization is in progress. Don't take any actions in Outlook during this period and you'll be safe.

Turn off your antivirus software

Sometimes outdated or over-protective anti-virus / anti-spam programs can conflict with Outlook or with one of your Outlook add-ins. As a result, the anti-virus blocks the add-in and prevents Outlook from functioning properly.

How do we deal with this? In the first place, check whether your antivirus is up-to-date. Reliable and trusted antivirus software vendors do care about compatibility with Microsoft Office applications, so there is a good chance that the issue is fixed in their latest update. (BTW, it's a good idea to check whether the latest updates and service packs are installed for your Microsoft Office as well.) Also, make sure that Outlook itself and your Outlook add-ins are added to the trusted applications list of your protection software. If the above does not help, turn off the antivirus and see if it brings Outlook back to life. If it does, the problem is definitely in your antivirus software. In this case, you can either contact its vendor for assistance or simply choose another protection program.

Repair your Office programs

If none of the above suggestions helped, try to repair your Office programs, as the last resort. Close all Office applications and open Control Panel. Find Microsoft Office in the list of installed programs (it is under "Programs and Features" on Vista, Windows 7 or Windows 8, and under "Add or Remove Programs" in earlier Windows versions) and right-click it. Select Change, then choose Repair and click the Continue button.
Repair Microsoft Office 2010

If you have never repaired your Office programs before, simply follow Microsoft's instructions for your version of Windows: Repair Office programs.

That seems to be all, I hope this information will help you solve the "Outlook not responding" problem efficiently. If you have any questions, drop me a comment and I will try to help.

113 comments

  1. Reference # 18. I was having the exact same issue as Andrea.

    I could successfully open the program in Safe Mode. I unchecked all Add-Ins.

    But it didn't make a difference. I would still receive "Not Responding" error when trying to boot-up Outlook in normal mode. I could only get rid of it by going to the Task Manager. Then Outlook would open and then not respond again. Ran Scanpst.exe several times but did not resolve issue.

    The ONLY thing that resolved it was turning off "Hardware acceleration" option in OUtlook in NORMAL mode.

    • Thanks Tony turning off "Hardware acceleration" option solved my issue

      Below are the steops

      Click File > Options to open the Outlook Options dialog box.

      In the Outlook Options dialog box, click Advanced in the left bar, and then check the Disable hardware graphics acceleration option in the Display section. See screenshot:

  2. It's really a good article and very helpful. Thanks a lot

  3. Actually, revise that statement:

    1) Close Outlook

    2) Go to task manager > Processes tab > highlight Outlook.exe and end process. Most likely it doesn't go away if your on this thread.

    3) Hold CTRL and open Outlook. When prompted select Yes to open in safe mode. As it starts to initalize simply close it back out.

    4) Open Command prompt > type taskkill /im outlook.exe /f

    5) Go to C:\Users\%USERPROFILE%\AppData\Local\Microsoft\Outlook and delete spscoll.dat, mapisvc.inf and your email account ending in.ost. If it won't let you delete your .ost file then simply drag it into your RoamCache folder.

    6) Outlook should now close out of your processes in task manager

    7) Go to start and type in repairpst.exe

    8) Ponit the applet to your attached .pst file and let it run. If you have more than one then repair all.

    9) After repairing .pst file(s) hold CTRL and launch Outlook again in Safe Mode. If all works well then close it out and try opening it normally.

    Cheers.

    • taskkill /im outlook.exe /f worked when all other suggestions did not. Thank you!

  4. Go to C:\Users\%USERPROFILE%\AppData\Local\Microsoft\Outlook and delete spscoll.dat. As soon as I got rid of it outlook finally disappeared from my task manager process list.

  5. Hi,

    I am having the 'not responding' Problem with a customers Outlook 2010 running on a Windows 7 64 Bit Machine as well.

    Outlook crashes as soon as it starts up, even in safe mode.

    What i tried so far :

    * scan.pst
    * Repair Office Suite
    * Reinstalling Office Suite (with the FixIt Tool to completely clean registry as well)
    * Set up new profiles

    It always starts with no errors after setting up and while synchronising the inbox i can restart Outlook as many times as i want, but as soon as the synchronisation is complete, Outlook hangs again after being restarted.

    Last test now I'm doing now is to use Outlook on the same machine with a new windows profile ... still snychronising and waiting for it to complete.

    Any other suggesiotns ?

    • Hi Florian,

      I can only suggest doing one of the following:

      1 Turn off all the add-ins.
      2 Temporarily disable your antivirus software.
      3 Contact Microsoft support service (support.microsoft.com) regarding this issue. They may help you better.

      • After several days in contact with the office365 support we now found out that the problem was due to an iCloud iCalender. After we disconnected this calender Outlook works fine again

  6. need expert suggestion - I Have issue with 2013 outlook. all the time I will get not responding and I need to kill the service and restart it. we have office 365 service hosted in Microsoft and using MS office stander edition.

  7. still having problems. tried everything. in fact, things are worse. after cleaning up the pst files, now my outlook is looking for a backup file that I deleted. I've re-booted the computer, I've tried to repair outlook and Microsoft office, but I get message saying that it can't do it!!
    Need to get work done, and I am at the end of my rope here!

  8. Hi all,
    I do all thmgs..but same issue

    • Hi Vinth,

      I am sorry to hear this. Please try contacting Microsoft support service regarding your issue.

  9. thanks A LOT - I found that a bloody webex productivity was killing my processes and freezing outlook up to a minute... killed it and this is working fine and dandy :)

  10. Hi,

    I am using Outlook 2010 and I'm trying to activate or setup the automatic replies, but it goes something like hanging and then pop up appears and it say " Your automatic reply setting cannot displayed because the server is currently unavailable. Try again later". but I check to the other users in our office it's all fine and working. My O/S was Windows 7 / office 2010. pls. help for the solution, many thanks.

    • Hello jimbo,
      It is difficult for me to say what can cause the problem. You'd better address this question to your system administrator.

  11. I click on Outlook Express and the blue box that says Outlook Express 6 comes up and just stays there....frozen....and you put the pointer on the box and an hour glass shows. It never goes to our emails. It sounds like the computer might be trying to do something...not sure...so what is going on? Why does it not go on to our emails and just stays frozen like that.

    • Hi Jan,

      I am sorry I cannot suggest anything regarding Outlook Express because I do not use it. You can probably contact the Microsoft Support Team for assistance.

      • Thank you very much for your reply.

  12. The results are awesome

  13. Thak I could able to open in safe mode and its working yahoooo

  14. I believe I solved my problems by deleting a backup. I have backed up my personal folders when I upgraded my outlook to 2013 from 2007. After a few days I launched a search into the back up to find a file. Shortly after that outlook started crashing at start-up. When I ran the repair tool I noticed that it defaulted to the backup. I deleted the back up and ran a repair on the current files. Problem appears to be solved.

  15. In our case, emails would intermittently hang/stick in outbox when using Outlook 2013 with MS Exchange Server. Problem was solved by updating router firmware to latest version.

    • Hi Neil,

      Thank you very much for sharing your solution here!

  16. Hi Alexander,

    By any chance are you equally knowledgeable about the glitches going on with Windows Live Mail? Yes, I'm one of those weird people who uses Outlook for my calendar and Windows Live Mail for e-mail but it's suddenly causing me so much grief I may have to switch soon if I can't find a solution.

    Cheers,
    Andrea

    • IMHO, you'd better move to some other email client. From my experience, Microsoft's free tools leave much to be desired.

    • Fixed my problem of Outlook opening (thanks again :)) but now two sessions of Outlook open each time......not a real drama closing one but is there an easy fix??

  17. Another "virtual" beer is on its way Alexander :) Been having similar problems to Andrea for the last week or so and everything I've tried to correct to now has failed. So today went through all your steps 1 by 1 and no joy until I turned off the hardware acceleration as outlined in your link and bingo problem appears solved (fingers crossed!!). Thanks for posting such comprehensive and easy to understand instructions that gives us 'non techos' some hope of fixing ourselves. Much appreciated!

  18. Great solutions! Starting in Safe Mode as Administrator and removing the add-ins fixed the problem immediately. Thank you so much for your info - Microsoft should be paying you because their solutions are pathetic.

  19. a simple fix that has just worked for me is to switch to "basic" theme. Hopefully MS will produce a patch ;)

  20. Alexander, you are a genius! I have my computer geek friend over just now to try and help me with my Outlook. Even he couldn't figure it out. Then I remembered I posed this question on here, checked back, saw your reply and you solved it! It was the Hardware Acceleration option that was the issue. My computer geek friend thanks you too. I'd buy you a beer if I could! :)

    Cheers,
    Andrea

    • Andrea, thanks for a "virtual" beer anyway :)

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