之所以引起此问题，是因为在子域指向的项目的Web配置中，http运行时版本的设置不同.我删除了该行:

The problem was caused because the http runtime version was set differently in the web config for the project that the sub domain points to. I removed the line:

<httpRuntime targetFramework="4.5.1" />

通过网络配置完成了任务

from the web config and that did the job