Site won´t load if WPDM plugin active

Hi comunity,
I´ve this proglem. I´m using this plugin on my site for managing documents. I´ve updated the plugin last week to version 2.8.0 (Wordpres 4.3.1). After that my “front-end” site stop working. The “back-end” works fine. Login, logout, all operations in wp-admin. I searched the mistake everywhere, so then I disabled the plugins step by step and WPDM causes the problem. When it is disabled the site works.
These are the errors I get when it is activated:
Undefined index: pagenow in /nfsmnt/hosting1_2/e/d/ed0f1475-9334-4e34-9a06-2eb2ede0adae/pastinazavada.sk/web/wp-includes/link-template.php on line 2742

The code in link-template.php on that lines:

function get_home_url( $blog_id = null, $path = '', $scheme = null ) {
	$orig_scheme = $scheme;

	if ( empty( $blog_id ) || !is_multisite() ) {
		$url = get_option( 'home' );
	} else {
		switch_to_blog( $blog_id );
		$url = get_option( 'home' );
		restore_current_blog();
	}

	if ( ! in_array( $scheme, array( 'http', 'https', 'relative' ) ) ) {
		if ( is_ssl() && ! is_admin() && 'wp-login.php' !== $GLOBALS['pagenow'] )
			$scheme = 'https';
		else
			$scheme = parse_url( $url, PHP_URL_SCHEME );
	}

	$url = set_url_scheme( $url, $scheme );

	if ( $path && is_string( $path ) )
		$url .= '/' . ltrim( $path, '/' );

	/**
	 * Filter the home URL.
	 *
	 * @since 3.0.0
	 *
	 * @param string      $url         The complete home URL including scheme and path.
	 * @param string      $path        Path relative to the home URL. Blank string if no path is specified.
	 * @param string|null $orig_scheme Scheme to give the home URL context. Accepts 'http', 'https', 'relative' or null.
	 * @param int|null    $blog_id     Blog ID, or null for the current blog.
	 */
	return apply_filters( 'home_url', $url, $path, $orig_scheme, $blog_id );
}

Does anyone know what to do now?
Thank You for Your ansvers.

Michal

https://wordpress.org/plugins/download-manager/