运行所有MVC一直502，重启了iis服务，
之后弹出这个框：
之后的解决办法：
1. If you open the applicationhost,config file in VS while running as an administrator, can you save it?
2. Assuming you can, I wonder if there are permissions issues with one of the files under
%USERPROFILE%DocumentsIISExpressconfig. Try renaming (or deleting) the config folder and restart VS. It will recreate those files.