IMPORTANT UPDATEThe actual problem most certainly was due to Apparmor misconfiguration. On my Ubuntu 14.04 this hack is no longer needed and in fact will break your Akonadi with
[16134.738227] audit: type=1400 audit(1421321299.961:42): apparmor="DENIED" operation="open" profile="/usr/sbin/mysqld" name="/home/moo/.local/share/akonadi/mysql.conf" pid=12758 comm="mysqld" requested_mask="r" denied_mask="r" fsuid=1000 ouid=1000
If your Akonadi does not start the problem is most probably elsewhere.
I finally wanted to try KDE mail/calendar suit today. On my system Kmail has failed start up - Akonadi service failed with "Akonadi control process not registered at D-Bus" error.
Apparently this error is misleading - the problem has nothing to do with D-Bus.
akonadictl start reveals more details:
$ akonadictl start .... Database process exited unexpectedly during initial connection! executable: "/usr/sbin/mysqld-akonadi" arguments: ("--defaults-file=/home/moo/.local/share/akonadi/mysql.conf", "--datadir=/home/moo/.local/share/akonadi/db_data/", "--socket=/home/moo/.local/share/akonadi/socket-bar/mysql.socket") stdout: "" stderr: "Could not open required defaults file: /home/moo/.local/share/akonadi/mysql.conf Fatal error in defaults handling. Program aborted " exit code: 1 process error: "Unknown error"So what is actually failing is MySQL startup. Here comes the mystery: running
/usr/sbin/mysqld-akonadi ...with all of the above arguments actually fails:
$ /usr/sbin/mysqld-akonadi --defaults-file=/home/moo... Could not open required defaults file: /khome/zaar.hai/.local/share/akonadi/mysql.conf Fatal error in defaults handling. Program abortedHowever if you just copy
/tmpit will start flawlessly.
I was not able to understand this weirdness, but the cure was simple: fortunately this akonadi script is just a dumb wrapper that execs mysql. So I've edited
/home/moo/.config/akonadi/akonadiserverrc to launch mysql directly and akonadi started successfully.