back to article Is it Patch Blues-day for Outlook? Microsoft's email client breaks worldwide, leaves everyone stumped

Microsoft's desktop email client Outlook has stopped working worldwide for countless users, whether they are using it with an on-premises Exchange server or with the Office 365 cloud. When you try to start the software on Windows, it immediately crashes with the error code 0xc0000005. "Microsoft has borked Outlook," one Reg …

  1. NetBlackOps


    I received an attempt to exploit the Outlook flaw last night, so damned if you roll back, damned if you don't.

  2. jake Silver badge

    Other options

    "users and admins must decide between using an insecure email client, or no email client at all until Microsoft fixes the glitch."

    Or perhaps they can scream "ENOUGH!" and change to a real email system that doesn't provide headaches like this at mind bogglingly frequent intervals?

    1. Pirate Dave Silver badge

      Re: Other options

      I miss the days when Groupwise was cool...

      1. gerdesj Silver badge

        Re: Other options

        I have a customer who is still using it for several hundred users. I use Evolution to connect to our corp Exchange.

        I missed this news when it was still exciting.

    2. mistersaxon

      Re: Other options

      MacOS version was unaffected also - so the issue is Windows, rather than Outlook...

  3. JassMan Silver badge

    So much for QA testing.

    If they didn't test it on more than 1 pc to check that it actually ran at all, how do they know the 123 fixes have actually worked?

    If yhey did actualy manage to get it running on more than 1 pc why don't they publish a recommended configuration for users to try before rolling back. As the article says, a number of the fixes are security critical and you don't really want to open up your system to crackers by reverting to a version with known attack vectors.

    1. JassMan Silver badge

      Re: So much for QA testing.

      I have just realised how ironic it would be if they only tested it on PCs running with WSL enabled 'cos you know that linux stuff is so flaky and if it runs on a PC setup like that, it will run on anything because Windows core is so reliable.

  4. cantankerous swineherd

    2021 and an email in the preview pane triggers a bug fgs.

    1. General Purpose Silver badge

      Still in 2020 here. Also borked.

  5. Inventor of the Marmite Laser

    Office 320

    And falling

  6. Claverhouse Silver badge

    I hope all the affected users immediately sent an angry email to Microsoft.

    1. sanmigueelbeer Silver badge

      I hope all the affected users immediately sent an angry email to Microsoft.

      A "reply-all" email storm would be sufficient.

  7. General Purpose Silver badge

    Digital distancing

    Outlook 2019 worked in safe mode.

  8. Anonymous Coward
    Anonymous Coward

    I'm guessing this only affects Windows versions?

    Mac version updated yesterday and seems to be working ok.

    1. Anonymous Coward
      Anonymous Coward

      Re: I'm guessing this only affects Windows versions?

      So far, I've avoided MS Office completely on my new Macbook - it's what I keep my old one for :).

      That way I know I have at least a system that stays clean.

      1. DJV Silver badge

        Re: I'm guessing this only affects Windows versions?

        I've avoided MS Office completely on my own systems for over 10 years. I've seen too much pain inflicted on those who don't realise that reasonable alternatives exist out there, to ever want to go back.

        1. Anonymous Coward
          Anonymous Coward

          Re: I'm guessing this only affects Windows versions?

          Unfortunately, I am beset with idiots that can't handle as much as a desktop background change without panicking, so trying to get them onto something that is actually safe is far more work than keeping a dirty laptop.

          In addition, I have kids at Uni who also "must" have MS Office per Uni diktat, but at least I managed to get them MacBooks and avoid Outlook.

          I've been watching this infestation from the days of MS-DOS, and the way they do business has not really improved. IMHO they're still mainly double glazed salesmen who employ a few coders.

          1. Anonymous Coward
            Anonymous Coward

            Re: I'm guessing this only affects Windows versions?

            When I switched from Windows to Mac in 2012 I started using Apple's own Mail app - and still find it does all I need from a mail app. I have around a dozen email accounts (some Exchange, some gmail, some common IMAP) and Mail lets me treat them as one for most purposes - whilst still letting me keep them separate when needed (such as for emails with students I tutor for the local college).

            I have Outlook installed (as part of Microsoft365 (ensures compatibility when dealing with others - I have LibreOffice on my Linux VM but rarely find I need to use it). I only fire up Outlook to search my pre2012 email archive (something I find I need to do once or twice a year).

            When I read about the Outlook glitch, it wasn't affecting Mac.

  9. Michael Hoffmann

    Once upon a time

    ... you could check your version by simply going Help->About. Version, patch level, useful stuff.

    Now I get the wall-of-text version of Clippy.

  10. TG2.2

    Was kinda funny / not so .. I have 5 different profiles, 2 of them have exchange/o365 in them, the other 3 do not, yet I couldn't restart my non-exchange profiles, hence reading "only effecting" ... I'm like.. right .. then why didn't my pop and imap only profiles fail .. then the cliffnote in this article (thank you TheRegister) that it was actually the Click-To-Run component which killed it.

    So .. while this officially was a glitch for Outlook / office .. what it proves, is that for no reason what so ever, if microsoft *wanted* to, they can block access to apps you've rightfully paid for, simply by throwing a switch. Way to go with your " "wardrobe malfunction" " microsoft, well done.

  11. MrNigel

    Back in the day....

    In the 90's I used to resell HP OpenMail (UNIX X.400/X.500 based) and the newly emerging Microsoft Exchange running on NT. I vividly remember doing a presentation to a Warrington based chemicals company when we got to the acetate about the upgrade process. We explained how to update both products including the bit where you had to reboot the Exchange Server. That was the point where we were reminded that they were a 24/7 manufacturing company and it was not acceptable to install products that required 'rebooting' when a patch/upgrade was applied. HP OpenMail got the order. #GoodOldDays

    1. Captain Scarlet Silver badge

      Re: Back in the day....

      hmm so that would have been Lotus Domino out as well on Windows (I know AIX versions had fast recovery but unfortunatley never got to play with that OS). I know the Notes Network and Cluster services could transfer to another server as long as the nsf was there, however my experience was users often had to click ok on an error message relating being unable to connect to the server (I probably configured something incorrectly).

    2. Anonymous Coward
      Anonymous Coward

      Re: Back in the day....

      I was involved in getting people online on the early Net, pre www-era..

      One of the outfits I visited had two setups running Lotus Mail postoffices. One rack was Windows (I think it was NT 3.5 or something, as I said, it's long ago), and one rack further were two 3U Linux boxes doing the same. The one guy running the Linux boxes wandered in once a week to check up, the Windows people (with the whole rack) were there every day to keep it running, yet had to deal with far less email.

      Plus ça change, plus c'est la même chose..

  12. TVC

    Thanks for nothing Microsoft.

    Thanks. Now I know why my standalone copy of outlook 2016 broke yesterday and why I wasted the whole evening. No error messages, nothing on the Internet. Tried to run in safe mode, rolling back, reinstalling, running fix up programs, etc. eventually started to work again.

    1. Anonymous Coward
      Anonymous Coward

      Re: Thanks for nothing Microsoft.

      why I wasted the whole evening

      Downloading a copy of Linux Mint would have been *way* quicker.


  13. Onen hag Oll
    Paris Hilton

    Where was the testing?

    I can understand if something obscure wasn't working; but to kill the application immediately on loading? That must have meant that testing must have been sadly lacking...or perhaps missing altogether?

    1. Anonymous Coward
      Anonymous Coward

      Re: Where was the testing?

      The testing is what just happened, when people started to notice it breaking things...

  14. Anonymous IV

    Outlook 2010

    Outlook 2010 worked last night, and still works fine this morning.

    What can have gone wrong?

    1. big_D Silver badge

      Re: Outlook 2010

      I am using Office 365 current branch at home and at work.

      Both were working fine after the update yesterday - local Exchange, Exchange Online, and IMAP accounts connected. I guess we were just lucky.

      1. The Real SteveP

        Re: Outlook 2010

        Me too - I have Office 2019, updated both Windows 10 and Office automatically yesterday, had no real issues. Before the update, Outlook started telling me that I needed a password for each of the three 365 mailboxes on different domains that I use, but clicking on each mailbox opened them normally with no need to re-enter passwords.

        I also use Zorin, which I like, but don't find the Linux email clients anything like as useful as Outlook.

  15. TechHeadToo

    I left Windows behind, thankfully, when I retired. Solely Mac or Linux on home built kit.

    The I had to have W10 to support my daughter.

    I had expected that W10 would be a big improvement. But no. The arrogant way in which MS insist on installing its junk. My daughter is disabled. She cannot cope with changes to screen designs or workflows. I have Macs over 20 years old with a UI which is instantly recognisable from the one on this machine.

    Also - the email has been working, continuously, without interruption, (as has the OS) all that time too.

  16. Richard 36

    How many errors can Microsoft make?

  17. Anonymous Coward
    Anonymous Coward

    Mobile version

    I know my mobile version isn't affected, but saw that there is an update for the Andriod version. I clicked on the "What's new" to see if was anything related, and it displayed "Show your Pride! Go to settings to turn on a visual theme inspired by the flags of the LGBTQI+ community."

  18. khjohansen

    They call it Patchy Blues Day

    - But Monday's just as bad!

  19. SotarrTheWizard

    Effing Micro$oft. . .

    . . . .had to uninstall Office. . . then use the M$ Uninstall clue, and steam-clean all of Orifice off my box. Then re-install from DVD. 2 hours wasted. . .

    1. ICL1900-G3 Bronze badge

      Re: Effing Micro$oft. . .

      Other vendors are available...

      I know it's not always as simple as that, and I do sympathise, but I am glad that I am now retired and choose my own setup, and MS doesn't get a look-in.

  20. Tree

    Try Eudora

    Eudora is better. No to all these updates that allow one to be tracked..

    1. jake Silver badge

      I prefer Alpine (was: Try Eudora)

      Although I'll admit to using Mutt occasionally.

  21. Kobus Botes


    An NGO where I volunteer to support their IT had a number of problems yesterday.....

    1). Internet access was flaky/weird. They had limited access in the sense that only a few websites I tried were accessible (FB could be accessed, but not El Reg, for instance). It looked like a DNS problem to me (pinging would display the IP address, but it could either not reach it or it would time out. Other sites would be unknown. I could also not discern any difference between local and foreign sites). I did wonder if it was not perhaps related to the DNS security problem that was patched on Tuesday ( but have no idea what their ISP use.

    2). Outlook could not connect to the mail server. That had started on Tuesday already. The Outlook client did not crash, though, on the two machines I checked.

    3). Their website was down (completely, meaning that it was not a local problem).

    A call to their ISP seemingly got everything up and running (their website was up late afternoon when I checked from home). This morning they (the NGO) sent a message to say that mail was still down.

    Makes me wonder if these problems were perhaps related (no idea what mail server they use, though).

    We' ll find out tomorrow.

    1. Kobus Botes

      Re: Mmmmmm

      Replying to my own post:

      Outlook is still a problem - it either times out connecting, or says the server is unreachable.

      Downloaded and installed Thunderbird, set it up and mail is flowing.

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