I eventually found out through the logs that the password was too weak. I was very confused for a while, though.
In case this is an issue with the browser: (Firefox 59 (64-bit) / Ubuntu 16.04).
Just thought I’d let you know 
Hehehe… this is not the error of Firefox or any browser this is the password problem if you try any special character with that, it does not show the weak password, and you can also try Firefox Support for any problem.