View source for Extra slash in address

Hi.
On second stage of install R 5.5.9 there is extra slash in address bar.
Then it shown in "Base URL" ans if not delete it it shown in address bar on all pages.
Screenshots :
https://hkar.ru/Yd0r
https://hkar.ru/Yd0s
https://hkar.ru/Yd0t
It' a little annoying.