diff --git a/wp-includes/canonical.php b/wp-includes/canonical.php
index 4bb5d312f..8ead88a0e 100644
--- a/wp-includes/canonical.php
+++ b/wp-includes/canonical.php
@@ -166,6 +166,8 @@ function redirect_canonical($requested_url=null, $do_redirect=true) {
 	$user_home = @parse_url(get_option('home'));
 	if ( isset($user_home['host']) )
 		$redirect['host'] = $user_home['host'];
+	if ( !isset($user_home['path']) )
+		$user_home['path'] = '/';
 
 	// Handle ports
 	if ( isset($user_home['port']) )
@@ -239,7 +241,7 @@ function redirect_canonical($requested_url=null, $do_redirect=true) {
 		if ( isset($redirect['port']) )
 		 	$redirect_url .= ':' . $redirect['port'];
 		$redirect_url .= $redirect['path'];
-		if ( $redirect['query'] )
+		if ( isset($redirect['query']) )
 			$redirect_url .= '?' . $redirect['query'];
 	}
 
diff --git a/wp-includes/plugin.php b/wp-includes/plugin.php
index dc7dfe681..ccf90260d 100644
--- a/wp-includes/plugin.php
+++ b/wp-includes/plugin.php
@@ -658,7 +658,7 @@ function _wp_filter_build_unique_id($tag, $function, $priority) {
 		if ( !isset($function[0]->wp_filter_id) ) {
 			if ( false === $priority )
 				return false;
-			$count = isset($wp_filter[$tag]) ? count((array)$wp_filter[$tag][$priority]) : 0;
+			$count = isset($wp_filter[$tag][$priority]) ? count((array)$wp_filter[$tag][$priority]) : 0;
 			$function[0]->wp_filter_id = $count;
 			$obj_idx .= $count;
 			unset($count);
diff --git a/wp-includes/post.php b/wp-includes/post.php
index 773dd2bba..53e131469 100644
--- a/wp-includes/post.php
+++ b/wp-includes/post.php
@@ -28,10 +28,8 @@
 function get_attached_file( $attachment_id, $unfiltered = false ) {
 	$file = get_post_meta( $attachment_id, '_wp_attached_file', true );
 	// If the file is relative, prepend upload dir
-	if ( 0 !== strpos($file, '/') ) {
-		$uploads = wp_upload_dir();
+	if ( 0 !== strpos($file, '/') && ( ($uploads = wp_upload_dir()) && false === $uploads['error'] ) )
 		$file = $uploads['basedir'] . "/$file";
-	}
 	 	
 	if ( $unfiltered )
 		return $file;