Ever get the cPanel error message "The security token is missing from your request" after with you were suddenly logged off? The error happening is a sometimes non-repeating way?
(There have been several threads re: that on cPanel Forums.)
For me, it only happened with Firefox. Clearing the cooke for the webhost using cPanel seemed to fix the problem, but the error (seemingly) randomly came back. (With IE, Edge and Chrome I never had this error.)
Luckily, the latest update, 56.0, seems to have fixed this problem.