serial console – respawning too fast

Connecting a headless host by serial console I got the following error:

...
INIT: Id "S0" respawning too fast: disabled for 5 minutes
INIT: Id "S0" respawning too fast: disabled for 5 minutes
INIT: Id "S0" respawning too fast: disabled for 5 minutes
INIT: Id "S0" respawning too fast: disabled for 5 minutes
INIT: Id "S0" respawning too fast: disabled for 5 minutes
...

The problem was caused by the following line in /etc/inittab:

S0:2345:respawn:/sbin/mgetty -b -r -s 115000 -p "Serial Console Login: " ttyS0

Changing the speed from 115000 to 115200 fixed the problem.