我正在开发一个项目，我想让我的代码保持最新的Symfony稳定版本，现在他们已经发布了新的稳定版本2.3.6，当我尝试升级时，我收到以下错误。
php composer.phar update
Loading composer repositories with package information
[ErrorException]
Undefined offset: 3
update [--prefer-source] [--prefer-dist] [--dry-run] [--dev] [--no-dev] [--lock] [--no-plugins] [--no-custom-installers] [--no-scripts] [--no-progress] [--with-dependencies] [-v|vv|vvv|--verbose] [-o|--optimize-autoloader] [packages1] ... [packagesN]