hello, after a quick search, i don’t found an answer, so i’m here.
The login buton dosen’t work. With the console of firefox, i have 
Uncaught TypeError: OC.getRootPath is not a function.
It’s an old 16.0.3 Nextcloud and before trying to upgrade him on the 20.0.2 i need to connect to save some apps settings datas. (Usualy i use it with shared directory and calendare on my PC apps, so i didn’t notice the death of web interface). I realy need help because i use it for work =/