try letting akonadi rebuild its database. There is propably a database error due to the fact that the database was created by a much older version of akonadi.
To that end, first klose any instances of kmail/kontact. Then open a console and type
If you enter it repeatadly, at some point you are going to get the answer that "akonadiserver is not running". After that, delete the database folder.
rm -rf $HOME/.local/share/akonadi*
Note that your settings are not going to be affected, they are stored in $HOME/.config/apps/akonadi and $HOME/.kde4/share/akonadi, you are only deleting the database cache. After that, restart akonadi.
Akonadi will detect the absence of its database and rebuild it.
You might also want to run akonadiconsole or akonaditray, both will allow you to configure your database backend.