我也面临着同样的问题。尽管遵循每一个答案，它没有工作。 然后我将“Inherits=namespace.class”更改为“Inherits=完全限定的组装名”，即“Inherits=namespace.class,assemblyname, Version=， Culture=， PublicKeyToken=” 希望能有所帮助。

我用很简单的方法修好了它。你所要做的就是删除ProjectName\bin文件夹中的所有文件，然后从Visual studio顶部菜单栏Build->Rebuild Solution再次重建项目，你就完成了。现在试着运行这个项目。这个过程在Visual Studio 2022中为我工作。

I faced the problem in VS 2017 out of no where, took my whole day going through 100 of solutions any of these didnt work. I then took my whole solution and started it on different machine having VS 2017 installation.. IT FINALLY WORKED. Than reinstalled VS 2017 on the original one and it started running on that too. I strongly recommend you try your solution on a different machine before wasting much time to debug it, bcz it is a BUG in VS 2017 as it seemed for me, have reported same to VS TEAM. Hope this helps any one in grief. Cheers.

尝试修改全局变量。Asax文件(简单添加一个空格的地方)，并重新运行。这将迫使内置的web服务器刷新和重新编译全局。asax文件。

也做一个清理和重建-应该修复问题

我也得到了同样的错误…检查您的虚拟目录的IIS配置，并确保属性- ASP。Net - asp。NET版本与项目属性-应用程序-目标框架相同。(这为我解决了这个错误。)

我关闭和重开了视觉工作室，它工作。