After installing Linux Mint 17 in a VM I started the Update Manager to get the latest updates, including kernel. In the details window I saw this error:
update-initramfs: Generating /boot/initrd.img-3.13.0-24-generic Warning: No support for locale: en_US.UTF-8
Thanks to Tip: fix for update-initramfs "No support for local ..." I found the cause and the solution.
Cause (quoting from the source post): "The problem is that /usr/share/initramfs- tools/hooks/root_locale is expecting to see individual locale directories in /usr/lib/locale, but locale-gen is configured to generate an archive file by default."
Solution: Run locale-gen again (but use directories not archive file) and then update-initramfs.
sudo locale-gen --purge --no-archive sudo update-initramfs -u -t
Note: I published this post originally at Linux Mint: “Warning: No support for locale: en_US.UTF-8″ in update-initramfs. Migrated to Nikola in February 2015.