This is a comment on Extra slash in address, posted by WikiAdmin at 13.05.2019 10:37

View source for 'base_url' in config_default.php

The '##base_url##' is defined in the config_default.php. In some settings like the use of a subdomain, e.g. ##~https://wiki.example.com/##, it adds an additional backslash if one condion is not met.

%%'base_url'	=> ($_SERVER['SERVER_PORT'] == 443
		? 'https'
		: 'http'
	) .
	'://' . $_SERVER['SERVER_NAME'].
	($_SERVER['SERVER_PORT'] != 80
		? ':' . $_SERVER['SERVER_PORT']
		: ''
	) .
	'/' . preg_replace('/\/\//', '\/', trim(strtr(dirname($_SERVER['SCRIPT_NAME']), '\\', '/'), '/')) . '/' ,%%

We need to add also the other condition so it won't add the extra slash. 

FIXED: revision:efdb3b5