However, the problem still occurs but on my other computer. The following information appeared in the console (F12 in the browser):
login:310
Uncaught TypeError: Cannot read property 'substring' of undefined
at Object.success (login:310)
at c (jquery-1.10.2.min.js:3)
at Object.fireWith [as resolveWith] (jquery-1.10.2.min.js:3)
at k (jquery-1.10.2.min.js:5)
at XMLHttpRequest.r (jquery-1.10.2.min.js:5)