Outlook 2016 Sharepoint Calendar - started throwing authentication protocol error

[Dev Lunsford]

Hi, Outlook 2016 users (me included) are reporting this error message when their Outlook 2016 is connected to a Sharepoint calendar:

This has literally just started yesterday, and I've just had a bunch of Office updates including Outlook KB3118375 (which doesn't specifically mention this), or it might be one of the other general Office updates not specific to Outlook. Has anyone else seen this and is there anything we can do other than removing whichever update we find causes it? Do I need to report this somewhere? Thanks

Dev

[#2]

Also looking into this update which could be relevant https://support.microsoft.com/en-us/kb/3118293. I'm going to try removing each of them and let you know what I find out.

[#3]

After removing update KB3118375 and then KB3118293, the error box is still present. I also have (may already have had?) a send/receive error 0x80070005/HTTP 401 relating to the same Sharepoint Calendar list:

 In fact, each time I remove these updates and restart, and then look in my installed updates, one of them is back - so I can't reliably say that it's not caused by one of them...