Minecraft Realms Not Working – Minecraft Servers Down, Minecraft Server Status, Why Wont My Minecraft Update – Minecraft is currently down and preventing online play. This is appears to be due to the new Nether Update which launched today.
The engineers at Mojang are hard at work trying to restore the service.
UPDATE – 18:04 BST – Minecraft sign-in issues persist for some users
UPDATE – 16:14 BST – Minecraft sign-in issues persist
In the meantime, you can check DownDetector to confirm the status of the Minecraft servers.