User-Agent:       Mozilla/5.0 (X11; Linux x86_64; rv:45.0) Gecko/20100101 Firefox/45.0
Build Identifier: 

I have been accessing a MS Exchange Server using EWS with Evolution client without difficulty for a while, (OS 13.1, OS, 13.2 and LEAP 42.1 (since December 2015).

Now and again I was getting messages asking for my credentials again. These messages usually stop coming after a while, even if I do not renew my credentials. I just assume that there is a problem in the handshake with the server that gets solved after a while (e.g. server is down until restarted, timeout on the handshake, etc)

Now, however, although the MS Exchange server is up and running (proven by webmail access), I am continually getting access complaints from the server.

It seems that the cause of the problem lies in recent OpenSUSE updates (i.e. within the last two weeks, after 5.4.2016). I started my laptop for the first time since then and there were no problems with Evolution. I updated the 175 (!) packages that had become out of date in the meantime. Thereafter the authentication requests started coming every few seconds or so. A reboot did not help. 

I am using:
Evolution 3.16.5-4.8
Evolution-ews 3.16.5-2.3
Gnome 3.16.2 

Reproducible: Always