Ubuntu 23.04 (Lunar Lobster) の EOL は 2024年1月25日。
"Ubuntu announced its 23.04 (Lunar Lobster) release almost 9 months ago, on April 20, 2023 and its support period is now nearing its end. Ubuntu 23.04 will reach end of life on January 25, 2024."
Ubuntu Fridge | Ubuntu 23.04 (Lunar Lobster) reaches End of Life on January 25, 2024 https://fridge.ubuntu.com/2023/12/15/ubuntu-23-04-lunar-lobster-reaches-end-of-life-on-january-25-2024/