Comment # 1 on bug 1188122 from Stakanov Schufter

So, a bit more information, as the problem persists. 

As it appears, you run into it when you have a Gnome and a KDE applicatino
asking simultaneously for access to kwallet integration. 

In my case Gajim (which has the issue when asking for a password for the tor
driven xmpp client (probably because it takes a long time to establish the
connection, hence holds the grip on kwallet waiting) and Kmail started
automatically during system start up. In this context, you will after a while
or immediately, depends, run into it. 

To get out of the problem:

One program can stay open (in my case gajim). You need to exit kontact and
close with "ignore" all windows asking for passwords (not with "O.K.), because
otherwise the password will be erased). 

Close the kwalletmanager app in the tray with "exit".

Now open a terminal and do akonadictl restart. 

Wait for the server having been restarted, then start Kontakt. Kmail will now
have again access to the passwords deposited in the kwallet.