ASP.NET - .NET Framework 기본 예제에서 System.Web에 대한 System.IO.FileNotFoundException 예외 발생
이상하군요, 예전에는 안 그랬던 것 같은데 최근에 테스트할 일이 있어 생성했더니, Visual Studio의 Output 실행 로그에 System.IO.FileNotFoundException이 있습니다.
...[생략]...
'iisexpress.exe' (CLR v4.0.30319: /LM/W3SVC/2/ROOT-1-133528209075464738): Loaded 'C:\Windows\Microsoft.NET\Framework64\v4.0.30319\Temporary ASP.NET Files\vs\14fe66ee\42b634d7\App_Web_4wtwjhrw.dll'. 
Exception thrown: 'System.IO.FileNotFoundException' in mscorlib.dll
'iisexpress.exe' (CLR v4.0.30319: DefaultDomain): Loaded 'C:\WINDOWS\Microsoft.Net\assembly\GAC_MSIL\System.Drawing\v4.0_4.0.0.0__b03f5f7f11d50a3a\System.Drawing.dll'. 
...[생략]...
역시 이번에도 ^^; 그냥 지나칠 수가 없군요, 비주얼 스튜디오에서 "System.IO.FileNotFoundException" 예외에 대해 
Thrown 옵션을 켜면 이런 예외 메시지를 보게 됩니다.
System.IO.FileNotFoundException
  HResult=0x80070002
  Message=Could not load file or assembly 'System.Web' or one of its dependencies. The system cannot find the file specified.
  Source=mscorlib
  StackTrace:
   at System.Reflection.RuntimeAssembly._nLoad(AssemblyName fileName, String codeBase, Evidence assemblySecurity, RuntimeAssembly locationHint, StackCrawlMark& stackMark, IntPtr pPrivHostBinder, Boolean throwOnFileNotFound, Boolean forIntrospection, Boolean suppressSecurityChecks)
   at System.Reflection.RuntimeAssembly.InternalLoadAssemblyName(AssemblyName assemblyRef, Evidence assemblySecurity, RuntimeAssembly reqAssembly, StackCrawlMark& stackMark, IntPtr pPrivHostBinder, Boolean throwOnFileNotFound, Boolean forIntrospection, Boolean suppressSecurityChecks) in System.Reflection\RuntimeAssembly.cs:line 578
  This exception was originally thrown at this call stack:
    System.Reflection.RuntimeAssembly.InternalLoadAssemblyName(System.Reflection.AssemblyName, System.Security.Policy.Evidence, System.Reflection.RuntimeAssembly, ref System.Threading.StackCrawlMark, System.IntPtr, bool, bool, bool) in RuntimeAssembly.cs
더불어 Call Stack 창을 보면,
>    mscorlib.dll!System.Reflection.RuntimeAssembly.InternalLoadAssemblyName(System.Reflection.AssemblyName assemblyRef, System.Security.Policy.Evidence assemblySecurity, System.Reflection.RuntimeAssembly reqAssembly, ref System.Threading.StackCrawlMark stackMark, System.IntPtr pPrivHostBinder, bool throwOnFileNotFound, bool forIntrospection, bool suppressSecurityChecks) Line 575   C#
    mscorlib.dll!System.Reflection.RuntimeAssembly.InternalLoad(string assemblyString, System.Security.Policy.Evidence assemblySecurity, ref System.Threading.StackCrawlMark stackMark, System.IntPtr pPrivHostBinder, bool forIntrospection) Line 511  C#
    mscorlib.dll!System.Reflection.RuntimeAssembly.InternalLoad(string assemblyString, System.Security.Policy.Evidence assemblySecurity, ref System.Threading.StackCrawlMark stackMark, bool forIntrospection) Line 498 C#
    mscorlib.dll!System.Reflection.Assembly.Load(string assemblyString) Line 538    C#
    System.Web.dll!System.Web.Configuration.CompilationSection.LoadAssembly(string assemblyName = "System.Web", bool throwOnFail = true)    Unknown
    System.Web.Extensions.dll!System.Web.UI.AssemblyCache.Load(string assemblyName = "System.Web")  Unknown
    System.Web.Extensions.dll!System.Web.UI.ScriptResourceMapping.GetDefinition(System.Web.UI.ScriptReference scriptReference)  Unknown
    System.Web.Extensions.dll!System.Web.UI.ScriptReference.ScriptEffectiveInfo.ScriptEffectiveInfo(System.Web.UI.ScriptReference scriptReference = {System.Web.UI.ScriptReference})    Unknown
    System.Web.Extensions.dll!System.Web.UI.ScriptReference.GetAssembly(System.Web.UI.ScriptManager scriptManager = {System.Web.UI.ScriptManager})  Unknown
    System.Web.Extensions.dll!System.Web.UI.ScriptReference.IsAjaxFrameworkScript(System.Web.UI.ScriptManager scriptManager = {System.Web.UI.ScriptManager})    Unknown
    System.Web.Extensions.dll!System.Web.UI.ScriptManager.AddScriptCollections(System.Collections.Generic.List<System.Web.UI.ScriptReferenceBase> scripts = Count = 2, System.Collections.Generic.IEnumerable<System.Web.UI.ScriptManagerProxy> proxies = null) Unknown
    System.Web.Extensions.dll!System.Web.UI.ScriptManager.RegisterScripts() Unknown
ScriptManager라는 점에서 "Site.Master" 파일에 있는,
<%@ Master Language="C#" AutoEventWireup="true" CodeBehind="Site.master.cs" Inherits="WebApplication1.SiteMaster" %>
<!DOCTYPE html>
<html lang="en">
<head runat="server">
    ...[생략]...
</head>
<body>
    <form runat="server">
        <asp:ScriptManager runat="server">
            <Scripts>
                <%--To learn more about bundling scripts in ScriptManager see https://go.microsoft.com/fwlink/?LinkID=301884 --%>
                <%--Framework Scripts--%>
                <asp:ScriptReference Name="MsAjaxBundle" />
                <asp:ScriptReference Name="jquery" />
                <asp:ScriptReference Name="WebForms.js" Assembly="System.Web" Path="~/Scripts/WebForms/WebForms.js" />
                <asp:ScriptReference Name="WebUIValidation.js" Assembly="System.Web" Path="~/Scripts/WebForms/WebUIValidation.js" />
                <asp:ScriptReference Name="MenuStandards.js" Assembly="System.Web" Path="~/Scripts/WebForms/MenuStandards.js" />
                <asp:ScriptReference Name="GridView.js" Assembly="System.Web" Path="~/Scripts/WebForms/GridView.js" />
                <asp:ScriptReference Name="DetailsView.js" Assembly="System.Web" Path="~/Scripts/WebForms/DetailsView.js" />
                <asp:ScriptReference Name="TreeView.js" Assembly="System.Web" Path="~/Scripts/WebForms/TreeView.js" />
                <asp:ScriptReference Name="WebParts.js" Assembly="System.Web" Path="~/Scripts/WebForms/WebParts.js" />
                <asp:ScriptReference Name="Focus.js" Assembly="System.Web" Path="~/Scripts/WebForms/Focus.js" />
                <asp:ScriptReference Name="WebFormsBundle" />
                <%--Site Scripts--%>
            </Scripts>
        </asp:ScriptManager>
        ...[생략]...
</body>
</html>
System.Web과 관련된 ScriptReference가 영향을 주는 듯합니다. 실제로, WebForms.js부터 Focus.js까지 주석 처리를 하면 FileNotFoundException 예외가 발생하지 않습니다.
First-chance exception으로만 발생하고 Secondary-chance exception으로 연결이 안 된다는 점과, 해당 ScriptReference들이 모두 잘 동작한다는 점에서, 아마도 System.Web 이름으로 찾지 못했더라도 다른 식으로라도 로딩을 해 정상적으로 처리하는 것 같습니다.
단지, 저 오류를 디버그 창에서라도 보고 싶지 않다면 2가지 방법으로 처리할 수 있습니다. 첫 번째는, Global.asax.cs 파일에 "System.Web"에 대한 로딩 처리를 추가해 주는 것입니다.
public class Global : HttpApplication
{
    void Application_Start(object sender, EventArgs e)
    {
#if DEBUG
        AppDomain.CurrentDomain.AssemblyResolve += CurrentDomain_AssemblyResolve;
#endif
        // Code that runs on application startup
        RouteConfig.RegisterRoutes(RouteTable.Routes);
        BundleConfig.RegisterBundles(BundleTable.Bundles);
    }
    private System.Reflection.Assembly CurrentDomain_AssemblyResolve(object sender, ResolveEventArgs args)
    {
        foreach (var asm in AppDomain.CurrentDomain.GetAssemblies())
        {
            if (asm.GetName().Name == args.Name)
            {
                return asm;
            }
        }
        return null;
    }
}
저 코드가 싫다면, 두 번째 방법으로 Site.Master의 ScriptReference에 System.Web의 Strong name을 지정해도 됩니다.
<asp:ScriptReference Name="WebForms.js" Assembly="System.Web, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a" Path="~/Scripts/WebForms/WebForms.js" />
<asp:ScriptReference Name="WebUIValidation.js" Assembly="System.Web, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a" Path="~/Scripts/WebForms/WebUIValidation.js" />
<asp:ScriptReference Name="MenuStandards.js" Assembly="System.Web, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a" Path="~/Scripts/WebForms/MenuStandards.js" />
<asp:ScriptReference Name="GridView.js" Assembly="System.Web, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a" Path="~/Scripts/WebForms/GridView.js" />
<asp:ScriptReference Name="DetailsView.js" Assembly="System.Web, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a" Path="~/Scripts/WebForms/DetailsView.js" />
<asp:ScriptReference Name="TreeView.js" Assembly="System.Web, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a" Path="~/Scripts/WebForms/TreeView.js" />
<asp:ScriptReference Name="WebParts.js" Assembly="System.Web, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a" Path="~/Scripts/WebForms/WebParts.js" />
<asp:ScriptReference Name="Focus.js" Assembly="System.Web, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a" Path="~/Scripts/WebForms/Focus.js" />
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