Adding in file functions.php

upload-svg-file.php

add_filter('upload_mimes', 'custom_upload_mimes');

function custom_upload_mimes ( $existing_mimes=array() ) {

	// add the file extension to the array

	$existing_mimes['svg'] = 'mime/type';

        // call the modified list of extensions

	return $existing_mimes;

}