Index: src/wp-admin/includes/class-wp-filesystem-ftpext.php
===================================================================
--- src/wp-admin/includes/class-wp-filesystem-ftpext.php	(revision 31800)
+++ src/wp-admin/includes/class-wp-filesystem-ftpext.php	(working copy)
@@ -275,6 +275,11 @@
 	 */
 	public function exists($file) {
 		$list = @ftp_nlist($this->link, $file);
+
+		if ( empty( $list ) && $this->is_dir( $file ) ) {
+			return true; // File is an empty directory.
+		}
+
 		return !empty($list); //empty list = no file, so invert.
 	}
 	/**
Index: src/wp-admin/includes/class-wp-filesystem-ftpsockets.php
===================================================================
--- src/wp-admin/includes/class-wp-filesystem-ftpsockets.php	(revision 31800)
+++ src/wp-admin/includes/class-wp-filesystem-ftpsockets.php	(working copy)
@@ -274,6 +274,11 @@
 	 */
 	public function exists( $file ) {
 		$list = $this->ftp->nlist( $file );
+
+		if ( empty( $list ) && $this->is_dir( $file ) ) {
+			return true; // File is an empty directory.
+		}
+
 		return !empty( $list ); //empty list = no file, so invert.
 		// Return $this->ftp->is_exists($file); has issues with ABOR+426 responses on the ncFTPd server.
 	}