Without knowing your OS/version - errors such as you are receiving found on SunSolve - some solutions (use only if the problem discribed is what you are having) (I would first check diskspace for /var - if it's full and can't write to the file it will cause this error - this has happened before in my experience)


1.

On a headless system with the console directed to serial port a,
boot up messages are seen but no login prompt is displayed.

The output of the ps -ef|grep /dev/console command does not show the
/usr/lib/saf/ttymon process for the /dev/console device.

Executing that process manually per the last line in /etc/inittab does produce a
login prompt and the /dev/console process starts to run, but attempts to login to
the serial console return:
No utmpx entry.
The user must execute "login" from lowest level "shell" and the console login process dies.

This problem is caused by changing the console login entry in
/etc/inittab from respawn to off.

To fix the problem, change the line back to respawn and execute the init q command to
reread inittab. The console process should start normally, the user can login, and that process
will respawn if killed.

If it is still not working, type:

# cat /dev/null > /var/adm/utmpx
# cat /dev/null > /var/adm/wtmpx

This will clean the utmpx and wtmpx, which will fix the problem


2.
Problem
During login "file system full" errors are seen and login fails with
the message "No utmpx entry".

This is caused by a full file system and the system has no space
to write its utmpx (login info) entry.

To get around this condition the system must be booted up
into single user mode. Then clear (do not delete) the files:

/var/adm/utmp
/var/adm/utmpx

This can be done by typing:

#cat /dev/null > filename

This command will zero out the file but keep it there with
the correct permissions.

In some cases after removing these files your /var filesystem may
still be full. In this case type:

du -askd /var |sort -nr |more

This will give you a listing of the files from largest to smallest
on the /var filesystem.

In order to create space you may zero out the following files:

/var/cron/log
/var/spool/lp/logs
/var/adm/messages

You may also check the following for any large files that can be deleted:

/.wastebasket
/lost+found

----------------------------------------------------
Subsequent logins should work fine after this.