An error occurred while trying to save the iCloud account
On my iPhone 5S (with iOS 7.1.1) I find that the device has suddenly logged out of iCloud. I tried going to Setttings > iCloud and logging in again but I keep getting a message "An error occurred while trying to save the iCloud account". This appears after about 30 seconds of the "Verifying" message appearing when I click "Sign in".
My contacts, email and calendar which were linked to Google have also disappeared (they were working fine yesterday and no changes have been made since).
Would appreciate any pointers on how to resolve this issue? Thanks.