An error occurred while starting the application

问题

An error occurred while starting the application.
.NET Core 4.6.27617.05 X64 v4.0.0.0 | Microsoft.AspNetCore.Hosting version 2.2.0-rtm-35687 | Microsoft Windows 6.3.9600 | Need help?

本地与测试库正常，发布到正式环境IIS报这个错误，首先这个错误，不是版本问题，就是具体错误信息没给显示到页面上被屏蔽了，需要先将真正的报错原因显示出来。

解放方案

打开该网站的站点-发布目录文件夹，找到web.config文件
打开web.config找到stdoutLogEnabled=“false”，把该值改为true，即->stdoutLogEnabled=“true”

<?xml version="1.0" encoding="utf-8"?>
<configuration>
  <location path="." inheritInChildApplications="false">
    <system.webServer>
      <handlers>
        <add name="aspNetCore" path="*" verb="*" modules="AspNetCoreModuleV2" resourceType="Unspecified" />
      </handlers>
      <aspNetCore processPath="dotnet" arguments=".\YDB.GeneralSystem.RenBao.dll" stdoutLogEnabled="false" stdoutLogFile=".\logs\stdout" hostingModel="InProcess" />
    </system.webServer>
  </location>
</configuration>

重启IIS，再次触发这个报错，日志将会写在网站根目录下（IIS-网站-浏览） logs 文件下

![在这里插入图片描述](https://img-blog.csdnimg.cn/5d1c8cbde03547c6af6ba179eed38e45.png?x-oss-process=image/watermark,type_d3F5LXplbmhlaQ,shadow_50,text_Q1NETiBA5qmZ6Imy6Ziz5YWJ,size_20,color_FFFFFF,t_30,g_se,x_16

根据时间打开最近的.log 看下具体报错

Application startup exception: System.IO.FileNotFoundException: Could not load file or assembly 'AutoMapper, Version=9.0.0.0, Culture=neutral, PublicKeyToken=be96cd2c38ef1005'. 系统找不到指定的文件。
File name: 'AutoMapper, Version=9.0.0.0, Culture=neutral, PublicKeyToken=be96cd2c38ef1005'
   at YDB.GeneralSystem.RenBao.Startup.ConfigureServices(IServiceCollection services)
--- End of stack trace from previous location where exception was thrown ---
   at Microsoft.AspNetCore.Hosting.ConventionBasedStartup.ConfigureServices(IServiceCollection services)
   at Microsoft.AspNetCore.Hosting.Internal.WebHost.EnsureApplicationServices()
   at Microsoft.AspNetCore.Hosting.Internal.WebHost.Initialize()
--- End of stack trace from previous location where exception was thrown ---
   at Microsoft.AspNetCore.Hosting.Internal.WebHost.BuildApplication()


crit: Microsoft.AspNetCore.Hosting.Internal.WebHost[6]
      Application startup exception
System.IO.FileNotFoundException: Could not load file or assembly 'AutoMapper, Version=9.0.0.0, Culture=neutral, PublicKeyToken=be96cd2c38ef1005'. 系统找不到指定的文件。
File name: 'AutoMapper, Version=9.0.0.0, Culture=neutral, PublicKeyToken=be96cd2c38ef1005'
   at YDB.GeneralSystem.RenBao.Startup.ConfigureServices(IServiceCollection services)
--- End of stack trace from previous location where exception was thrown ---
   at Microsoft.AspNetCore.Hosting.ConventionBasedStartup.ConfigureServices(IServiceCollection services)
   at Microsoft.AspNetCore.Hosting.Internal.WebHost.EnsureApplicationServices()
   at Microsoft.AspNetCore.Hosting.Internal.WebHost.Initialize()
--- End of stack trace from previous location where exception was thrown ---
   at Microsoft.AspNetCore.Hosting.Internal.WebHost.BuildApplication()


Hosting environment: Production
Content root path: D:\www\XXXXXX\XXXX
Application started. Press Ctrl+C to shut down.

我这里是少这个文件AutoMapper 说在在ConfigureServices调用了依赖注入，但是找到对应的.dll然后就挂了， 就是同事添加了新代码暂时被撤销了，依赖注入这里没有对应撤销导致的，将依赖注入中AutoMapper删除就好了