报错信息：

HTTP Error 500.31 - Failed to load ASP.NET Core runtime
Common solutions to this issue:
The specified version of Microsoft.NetCore.App or Microsoft.AspNetCore.App was not found.
Troubleshooting steps:
Check the system event log for error messages
Enable logging the application process' stdout messages
Attach a debugger to the application process and inspect
For more information visit: https://go.microsoft.com/fwlink/?LinkID=2028526

问题原因及解决方法：

1）可能是缺少ASP.NET Core Runtime运行时导致，解决此问题安装ASP.NET Core Runtime即可解决

下载地址：https://dotnet.microsoft.com/download/dotnet/3.1

2）可能由于应用程序池没有对站点文件夹的权限造成的。授予相应权限即可解决。