Yay - that was happen to me. Magically I had two iCloud accounts, both not working - and no way to delete one of them via Settings -> Internet Accounts. After a few hours of googling, debugging I got it working again. And as usual I'd like to share that solution, I think I'm not the only one with that problem ;) Be aware, that's a bomb solution, means it will reset all internet accounts - but also unfreeze all the broken stuff: sudo -v ; killall -9 accountsd com.apple.iCloudHelper ; defaults delete MobileMeAccounts ; mkdir ~/Library/Accounts/Backup ; mv ~/Library/Accounts/*.sqlite* ~/Library/Accounts/Backup/ ; killall -9 accountsd com.apple.iCloudHelper ; sudo reboot So, why does that happen? Apple uses sqlite as backend for storing the informations, and sometimes this single instance get corrupted. Have fun!
Hey, I'm Alex. I founded X-Warp, Infinimesh, Infinite Devices, Scalytics and worked with Cloudera, E.On, Google, Evariant, and had the incredible luck to build products with outstanding people in my life, across the globe.