- The OwinStartup attribute discovered in assembly 'YY.Web' referencing startup type 'YY.Web.Startup' conflicts with the attribute in assembly 'HBJK.Web' referencing startup type 'HBJK.Web.Startup' because they have the same FriendlyName ''. Remove or rename one of the attributes, or reference the desired type directly.
To disable OWIN startup discovery, add the appSetting owin:AutomaticAppStartup with a value of "false" in your web.config.
To specify the OWIN startup Assembly, Class, or Method, add the appSetting owin:AppStartup with the fully qualified startup class or configuration method name in your web.config.
原因：因為修改了項目的名字，在bin 文件夾下出現兩個bll文件一個是原來的
解決方法：只要刪除原來的bll文件就行。