In Ubuntu 8.04 Server, I was getting these messages every now and then:
perl: warning: Setting locale failed.
perl: warning: Please check that your locale settings:
LANGUAGE = (unset),
LC_ALL = (unset),
LANG = "en_US.utf8"
are supported and installed on your system.
perl: warning: Falling back to the standard locale ("C").
locale: Cannot set LC_CTYPE to default locale: No such file or directory
locale: Cannot set LC_MESSAGES to default locale: No such file or directory
locale: Cannot set LC_ALL to default locale: No such file or directory
To solve this, I just had to install language pack:
apt-get install language-pack-en-base
If this does not solve the problem, you may as well try:
dpkg-reconfigure locales
Hope this helps.