Outlook 365 suddenly won't open

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Hello; Outlook worked this morning, now it won't open, says to open in Safe Mode, but that doesn't work, tries to open for 5 seconds than nothing. Restarted PC and no help. Please advise! Steven F 603


168 Replies

We are having the same issue reported from multiple users.  ~School District in California 


Did your computer recently install updates?  If so, which ones?


@Joshua Bowers 

It auto=updates, so I don't know.... if others have same problem, then its Microsoft issue on their end?

Same problem this AM



Running into the same problem with 10 of my customers so far this morning. If anyone has any insight I would like to hear it

I've got the same situation. Today I've update WIN10 with the last ones: KB4565627, KB4565503, KB4557957, KB4561600

Outlook is still stuck in SAtaring...... mode. we have tried many things- is this a Microsoft problem with their server?@Steven_F_603 

It certainly seems to be related to an update or possibly an issue on MSFT@Steven_F_603 


Can you look at your Windows update history to see if any were installed today?


Go to your settings > Updates > View Update history.  It should tell you if there are any that were installed today.  


@Joshua Bowers 

No, 6-16-20 was my last Update..... looks like Outlook outage on Outage Map online. Sucks!

@Joshua Bowers 


I have this in my 365 Admin portal under Incidents.  So this seems to be an issue on their end.


Users experiencing Outlook connection issues and crashes
EX218604, Exchange Online, Last updated: July 15, 2020 10:02 AM
Start time: July 15, 2020 9:18 AM
Service degradation
User impact
Users may experience crashes or may be unable to access Exchange Online via Outlook.

Same issue for me.  I updated Office this morning in an attempt to fix the problem but it didn't help.  @Steven_F_603 

@Steven_F_603 there is currently a service incidence regarding can access your mailbox on the web and on your mobile Outlook client while it is been resolved


@Steven_F_603  Same here.  And with a friend in the same building who just came to me for help.  Seems it's a problem your end cos it was fine this morning, now we all have it...

Same issue here - I've tried Office repair 3x - rebooted. This occurred after recent Windows update last night.


@Ardamilola  Until such time as Outlook is fixed, how do I access my calendar? I don't have a mobile Outlook client.

@Steven_F_603 I also had the Windwos Updates this morning and my Outlook 365 wouldn't open since. It did open in Safe Mode (Outlook.exe /safe). I just did a System Restore from earlier this morning, from the restore point before the installation of these updates and now my Otlook open fine. Just to be sure, I stopped Windows Update for 5 days.



Did you go into the Office portal on the web? Should be able to get to it there.

I have two clients with this issue. Dont whatever you do attempt the online repair that Microsoft recommends. I tried that (could just be unlucky) but it got half way through then just said "something went wrong" and now the entire office suite home and business 2019 has just vanished off the computer.


Outlook 2016 as well. Slightly different behavior than Outlook 365 (which is also failing to open except in safe mode.) Outlook 2016 opens, and then closes automatically.


@GaryB1212Thank you.