Warning: stripos() expects parameter 1 to be string, array given in

you are trying to pass an array instead of string.

disable all plugins test again.

I disabled all plugins – still getting same errors

keep all plugins disable and
set theme to 2015 try again.

still error

her is line 3383 :

if ( 0 !== stripos( $url, ‘mailto:’ ) ) {

this is part of your function esc_url

if ( 0 !== stripos( $url, 'mailto:' ) ) {
		$strip = array('%0d', '%0a', '%0D', '%0A');
		$url = _deep_replace($strip, $url);
	}

A number of characters are removed from the URL. If the URL is for displaying (the default behaviour) ampersands are also replaced. The ‘clean_url’ filter is applied to the returned cleaned URL.

https://codex.www.ads-software.com/Function_Reference/esc_url

possibley starting with anything regarding mailto.
maybe your email address your using or the site url has extra characters

Was this ever fixed? WordPress 4.7.1 has caused me lots of trouble and I am trying to track down solutions. 4 of the sites I manage are down.