Here is the output when launching kontact from the cli. This is a fully updated install of natty. The user was created at install time. Kontact worked on a previous install of natty where the user had been created and kontact had been configured by a previous released version of kubuntu (10.10).
search paths: ("/home/valdiyen/.bin", "/usr/local/sbin", "/usr/local/bin", "/usr/sbin", "/usr/bin", "/sbin", "/bin", "/usr/games", "/usr/sbin", "/usr/local/sbin", "/usr/local/libexec", "/usr/libexec", "/opt/mysql/libexec", "/opt/local/lib/mysql5/bin", "/opt/mysql/sbin")
Found mysql_install_db: "/usr/bin/mysql_install_db"
Found mysqlcheck: "/usr/bin/mysqlcheck"
Database process exited unexpectedly during initial connection!
executable: "/usr/sbin/mysqld-akonadi"
arguments: ("--defaults-file=/home/valdiyen/.local/share/akonadi//mysql.conf", "--datadir=/home/valdiyen/.local/share/akonadi/db_data/", "--socket=/home/valdiyen/.local/share/akonadi/socket-isilme/mysql.socket")
stdout: ""
stderr: ""
exit code: 1
process error: "Unknown error"
"[
0: akonadiserver(_Z11akBacktracev+0x34) [0x44ad84]
1: akonadiserver() [0x44b2da]
2: /lib/libc.so.6(+0x33c20) [0x7fa6bae11c20]
3: /lib/libc.so.6(gsignal+0x35) [0x7fa6bae11ba5]
4: /lib/libc.so.6(abort+0x186) [0x7fa6bae154f6]
5: /usr/lib/libQtCore.so.4(_Z17qt_message_output9QtMsgTypePKc+0x74) [0x7fa6bca99964]
6: akonadiserver(_ZN15FileDebugStream9writeDataEPKcx+0x92) [0x44ccc2]
7: /usr/lib/libQtCore.so.4(_ZN9QIODevice5writeEPKcx+0x77) [0x7fa6bcb255c7]
8: /usr/lib/libQtCore.so.4(+0xfe8f3) [0x7fa6bcb2d8f3]
9: /usr/lib/libQtCore.so.4(_ZN11QTextStreamD1Ev+0x3b) [0x7fa6bcb366ab]
10: akonadiserver(_ZN6QDebugD1Ev+0x46) [0x446cc6]
11: akonadiserver(_ZN13DbConfigMysql19startInternalServerEv+0x193c) [0x4c8e0c]
12: akonadiserver(_ZN7Akonadi13AkonadiServer20startDatabaseProcessEv+0xd2) [0x44d122]
13: akonadiserver(_ZN7Akonadi13AkonadiServerC1EP7QObject+0xc2) [0x44e902]
14: akonadiserver(_ZN7Akonadi13AkonadiServer8instanceEv+0x37) [0x44ff37]
15: akonadiserver(main+0x2ae) [0x445e4e]
16: /lib/libc.so.6(__libc_start_main+0xfe) [0x7fa6badfcd1e]
17: akonadiserver() [0x445aa9]
]
"
ProcessControl: Application 'akonadiserver' returned with exit code 255 (Unknown error)
"akonadiserver" crashed too often and will not be restarted!
ProblemType: Bug
DistroRelease: Ubuntu 11.04
Package: akonadi-server 1.4.95-0ubuntu1
ProcVersionSignature: Ubuntu 2.6.37-12.26-generic 2.6.37
Uname: Linux 2.6.37-12-generic x86_64
Architecture: amd64
Date: Tue Jan 25 10:02:19 2011
EcryptfsInUse: Yes
InstallationMedia: Kubuntu 11.04 "Natty Narwhal" - Alpha amd64 (20110121)
ProcEnviron:
LANGUAGE=
PATH=(custom, user)
LANG=en_US.UTF-8
SHELL=/bin/bash
SourcePackage: akonadi
See bug 578357. The solution posted by Domenichelli worked for me.