No such user as string– cron entries not created

Cause
A file exists in /var/spool/cron/crontabs for the specified user, but this user is
not in /etc/passwd or the NIS passwd(4) map. The system cannot create
cron(1M) entries for nonexistent users.
Action
To eliminate this message at boot time, remove the cron file for the nonexistent user,
or rename it if the user’s login name has changed. If this is a valid user, create an
appropriate password entry for this name.

No utmpx entry

Cause
During login, file system full errors are seen and the login fails with the
message No utmpx entry.

This error is caused by a full file system. The system has no space to write its utmpx
(login information) entry.
Action
To correct this condition the system must be booted into single user mode. Then
clear (do not delete) these files: /var/adm/utmp and /var/adm/utmpx. This can be
done by typing:
#cat /dev/null > /var/adm/utmp
#cat /dev/null > /var/adm/utmpx
These commands zero-out the files but keep them with the correct permissions.
In some cases, after clearing these files, the /var file system might still be full. In
this case type:
du -askd /var |sort -nr |more
This command gives you a listing of the files from largest to smallest in the /var file
system. To create space you can zero these files: /var/cron/log,
/var/spool/lp/logs, and /var/adm/messages. You can also check
/.wastebasket for large files to delete.