asp.net core 3.1 问题
// 启用倒带功能,就可以让 Request.Body 可以再次读取
Request.EnableBuffering(); //((Microsoft.AspNetCore.Http.DefaultHttpRequest)Request).ContentLength
ASP.NET Core 中 HttpContext 详解与使用 | Microsoft.AspNetCore.Http 详解
https://www.cnblogs.com/whuanle/p/10077339.html#t41
asp.net core 2.2升到3.1遇到的问题小记
https://www.cnblogs.com/Wadereye/p/12287893.html