When I use 'Tools.Find Messages', enter a criterion and select 'Search', I get a notification, "Akonadi Server Closed Unexpectedly" and a dialogue box with the message, "The Akonadi personal information management service is not operational". Clicking the "Details" button highlights the button but has no other effect. 

If I exit kmail and restart, the dialogue box is still displayed, unless I do a akonadictl restart, in which case kmail starts normally (until I do another search).