Composer在更新时终止

Question

$ php composer.phar update
Loading composer repositories with package information
Updating dependencies (including require-dev)
Terminated

当我尝试更新symfony2应用程序中的依赖项时，

Composer终止。哪里有问题？

修改

我尝试运行composer diag，输出为：

Checking platform settings: OK
Checking http connectivity: OK
Checking composer.json:

  [ErrorException]
  Undefined index: require-dev

但是我的composer.json中没有“require-dev”行。