Snippet for the functions.php of your WordPress (child) theme to allow .svg as a file format.

allow svg in WordPress.php

#region Allow .svg files
function nxt_allow_svg($mimes) {
	$mimes['svg'] = 'image/svg+xml';
	return $mimes;
}
add_filter('upload_mimes', 'nxt_allow_svg');

function nxt_really_allow_svg($checked, $file, $filename, $mimes){
	if(!$checked['type']){
		$wp_filetype = wp_check_filetype( $filename, $mimes );
		$ext = $wp_filetype['ext'];
		$type = $wp_filetype['type'];
		$proper_filename = $filename;
		if($type && 0 === strpos($type, 'image/') && $ext !== 'svg'){
			$ext = $type = false;
		}	
		$checked = compact('ext','type','proper_filename');
	}
	return $checked;
}
add_filter('wp_check_filetype_and_ext', 'nxt_really_allow_svg', 10, 4);
#endregion Allow .svg files