The end of Ubuntu 11.04 means the end of Linux Mint 11
After Ubuntu 11.04 (Natty Narwhal) has reached end of life on October 28, development of Linux Mint 11, codenamed Katya, has also stopped.It’s not unusual for Linux distributions to make way for better operating systems. Canonical provides two years of support for each of its distributions, with the exception of LTS releases that benefit from five years of support.
Linux Mint 11 Katya was based on Ubuntu 11.04 (Natty Narwhal) so it’s only natural that the support for Linux Mint stops as well.
According to Linux Mint developers, the repositories will remain open, but no more updates or security fixes will be made available.
Users of Linux Mint 11 Katya are asked to migrate to “Linux Mint 13 LTS Maya – MATE Edition” (which will be supported until April 2017).