I've an ownCloud server running at home and created some calendars and contactlists to seperate private and university stuff and imported them using DAVGroupware. So I have calendars (caldav) and contactlists (carddav) with the same name ("Allgemein", "Uni"). Until KDE SC 4.10.1 this was no problem, but with the last update Akonadi told me it couldn't create resource with id 38. Both calendars and contactlists vanished from kontact. When I removed the contacts from the devresource and created an extra resource for them it works. So I think this is a problem with the names.
Steps to Reproduce:
1. Create DavGroupware with caldav and carddav sources which contain collections with the same name
2. wait till Akonadi complains and see it's not working
3. remove carddav resource and create new DavGroupware
4. see it's working now
Looks a lot like a duplicate of #284783, though I don't understand how it worked before.
*** This bug has been marked as a duplicate of bug 284783 ***