Thus, it can become a bit of a puzzle for anyone who faces it for the first time. What’s more, all the error pop-up mentions is that Outlook can’t open it specifies nothing about why or what to do about it. Herein we’re discussing about the “Outlook doesn’t open” error and easy methods to resolve it.īeing greeted with an error pop-up that says, “Cannot start Microsoft Outlook” could be rather irritating when all you want to do is confirm the exact time for your approaching meeting. If you’ve ever been in this situation, you should probably bookmark this article. But what do you do when Outlook simply doesn’t want to open? How do you fix an error when the very first step for it doesn’t complete? Usually, whenever an issue strikes MS Outlook, you can find numerous handy ways online to fix it. That are the registry keys that are mentioned in the blog post under the Outlook section.Among the many little errors that crop up unexpectedly while working with Outlook, lies the frustrating one where Outlook doesn’t open.

Once you reconcile the settings service side - there could still be settings client-side that are forcing your Outlook clients to use basic auth. The bottom line is - you should check your Message Center posts and Service Health Notifications to see if Microsoft made changes to authentication in your tenant before the problem started. I do not know that this is a problem, but be aware if you see something about it, this will block all basic auth outright. Modern auth could also be turned on in Azure by a setting called Security Defaults. That basically tells Outlook clients 'you can use modern auth'. As this is Outlook for Windows we are talking about - there is also a tenant setting as mentioned under Outlook section in that blog post. So first thing that needs to be understood is - which protocol is Outlook using to connect to Exchange Online? Is basic auth turned off for it? (running the diagnostics from that blog post will show you) Are those Outlook clients using POP/IMAP as a protocols or not? (this will depend on how profiles are created)

There is a per-protocols modern auth setting, which is what we are turning on for tenants starting October 1st when that happens, basically there is no more basic auth for a particular protocol.

Yeah so you need to clarify what it means that 'modern authentication has been turned on'.

Ms outlook 2013