error when using filehelpers on IIS; sometimes :S : [PolicyException: Required permissions cannot be acquired.]

FileHelpers.dll (2.0) are referenced within 2 class libraryies (Dto and Services) in my solution

My webapp (asp.net mvc) is on IIS7 (开发者_开发问答Full Trust) Windows 7 PRO 64 and I sometimes get this exception when starting my app from VS2008: (to get rid of it I delete the FileHelpers.dll from bin, run, close browser, rebuild the solution and run again )

     [PolicyException: Required permissions cannot be acquired.]
       System.Security.SecurityManager.ResolvePolicy(Evidence evidence, PermissionSet reqdPset, PermissionSet optPset, PermissionSet denyPset, PermissionSet& denied, Boolean checkExecutionPermission) +10238142
       System.Security.SecurityManager.ResolvePolicy(Evidence evidence, PermissionSet reqdPset, PermissionSet optPset, PermissionSet denyPset, PermissionSet& denied, Int32& securitySpecialFlags, Boolean checkExecutionPermission) +97

    [FileLoadException: Could not load file or assembly 'FileHelpers, Version=2.0.0.0, Culture=neutral, PublicKeyToken=3e0c08d59cc3d657' or one of its dependencies. Failed to grant minimum permission requests. (Exception from HRESULT: 0x80131417)]
       System.Reflection.Assembly._nLoad(AssemblyName fileName, String codeBase, Evidence assemblySecurity, Assembly locationHint, StackCrawlMark& stackMark, Boolean throwOnFileNotFound, Boolean forIntrospection) +0
       System.Reflection.Assembly.InternalLoad(AssemblyName assemblyRef, Evidence assemblySecurity, StackCrawlMark& stackMark, Boolean forIntrospection) +416
       System.Reflection.Assembly.InternalLoad(String assemblyString, Evidence assemblySecurity, StackCrawlMark& stackMark, Boolean forIntrospection) +166
       System.Reflection.Assembly.Load(String assemblyString) +35
       System.Web.Configuration.CompilationSection.LoadAssemblyHelper(String assemblyName, Boolean starDirective) +190

    [ConfigurationErrorsException: Could not load file or assembly 'FileHelpers, Version=2.0.0.0, Culture=neutral, PublicKeyToken=3e0c08d59cc3d657' or one of its dependencies. Failed to grant minimum permission requests. (Exception from HRESULT: 0x80131417)]
       System.Web.Configuration.CompilationSection.LoadAssemblyHelper(String assemblyName, Boolean starDirective) +11207304
       System.Web.Configuration.CompilationSection.LoadAllAssembliesFromAppDomainBinDirectory() +388
       System.Web.Configuration.CompilationSection.LoadAssembly(AssemblyInfo ai) +232
       System.Web.Configuration.AssemblyInfo.get_AssemblyInternal() +48
       System.Web.Compilation.BuildManager.GetReferencedAssemblies(CompilationSection compConfig) +210
       System.Web.Compilation.BuildProvidersCompiler..ctor(VirtualPath configPath, Boolean supportLocalization, String outputAssemblyName) +76
       System.Web.Compilation.ApplicationBuildProvider.GetGlobalAsaxBuildResult(Boolean isPrecompiledApp) +283
       System.Web.Compilation.BuildManager.CompileGlobalAsax() +50
       System.Web.Compilation.BuildManager.EnsureTopLevelFilesCompiled() +676

    [HttpException (0x80004005): Could not load file or assembly 'FileHelpers, Version=2.0.0.0, Culture=neutral, PublicKeyToken=3e0c08d59cc3d657' or one of its dependencies. Failed to grant minimum permission requests. (Exception from HRESULT: 0x80131417)]
       System.Web.Compilation.BuildManager.ReportTopLevelCompilationException() +76
       System.Web.Compilation.BuildManager.EnsureTopLevelFilesCompiled() +1012
       System.Web.Hosting.HostingEnvironment.Initialize(ApplicationManager appManager, IApplicationHost appHost, IConfigMapPathFactory configMapPathFactory, HostingEnvironmentParameters hostingParameters) +1025

[HttpException (0x80004005): Could not load file or assembly 'FileHelpers, Version=2.0.0.0, Culture=neutral, PublicKeyToken=3e0c08d59cc3d657' or one of its dependencies. Failed to grant minimum permission requests. (Exception from HRESULT: 0x80131417)]
   System.Web.HttpRuntime.FirstRequestInit(HttpContext context) +11301302
   System.Web.HttpRuntime.EnsureFirstRequestInit(HttpContext context) +88
   System.Web.HttpRuntime.ProcessRequestNotificationPrivate(IIS7WorkerRequest wr, HttpContext context) +4338644

I tried to switch to FileHelpers 1.6 which don't use reflection.emit and I get this exception:

    Stack Trace: 


[PolicyException: Required permissions cannot be acquired.]
   System.Security.SecurityManager.ResolvePolicy(Evidence evidence, PermissionSet reqdPset, PermissionSet optPset, PermissionSet denyPset, PermissionSet& denied, Boolean checkExecutionPermission) +10238142
   System.Security.SecurityManager.ResolvePolicy(Evidence evidence, PermissionSet reqdPset, PermissionSet optPset, PermissionSet denyPset, PermissionSet& denied, Int32& securitySpecialFlags, Boolean checkExecutionPermission) +97

[FileLoadException: Could not load file or assembly 'FileHelpers, Version=1.6.0.0, Culture=neutral, PublicKeyToken=null' or one of its dependencies. Failed to grant minimum permission requests. (Exception from HRESULT: 0x80131417)]
   System.Reflection.Assembly._nLoad(AssemblyName fileName, String codeBase, Evidence assemblySecurity, Assembly locationHint, StackCrawlMark& stackMark, Boolean throwOnFileNotFound, Boolean forIntrospection) +0
   System.Reflection.Assembly.InternalLoad(AssemblyName assemblyRef, Evidence assemblySecurity, StackCrawlMark& stackMark, Boolean forIntrospection) +416
   System.Reflection.Assembly.InternalLoad(String assemblyString, Evidence assemblySecurity, StackCrawlMark& stackMark, Boolean forIntrospection) +166
   System.Reflection.Assembly.Load(String assemblyString) +35
   System.Web.Configuration.CompilationSection.LoadAssemblyHelper(String assemblyName, Boolean starDirective) +190

[ConfigurationErrorsException: Could not load file or assembly 'FileHelpers, Version=1.6.0.0, Culture=neutral, PublicKeyToken=null' or one of its dependencies. Failed to grant minimum permission requests. (Exception from HRESULT: 0x80131417)]
   System.Web.Configuration.CompilationSection.LoadAssemblyHelper(String assemblyName, Boolean starDirective) +11207304
   System.Web.Configuration.CompilationSection.LoadAllAssembliesFromAppDomainBinDirectory() +388
   System.Web.Configuration.CompilationSection.LoadAssembly(AssemblyInfo ai) +232
   System.Web.Configuration.AssemblyInfo.get_AssemblyInternal() +48
   System.Web.Compilation.BuildManager.GetReferencedAssemblies(CompilationSection compConfig) +210
   System.Web.Compilation.BuildProvidersCompiler..ctor(VirtualPath configPath, Boolean supportLocalization, String outputAssemblyName) +76
   System.Web.Compilation.ApplicationBuildProvider.GetGlobalAsaxBuildResult(Boolean isPrecompiledApp) +283
   System.Web.Compilation.BuildManager.CompileGlobalAsax() +50
   System.Web.Compilation.BuildManager.EnsureTopLevelFilesCompiled() +676

[HttpException (0x80004005): Could not load file or assembly 'FileHelpers, Version=1.6.0.0, Culture=neutral, PublicKeyToken=null' or one of its dependencies. Failed to grant minimum permission requests. (Exception from HRESULT: 0x80131417)]
   System.Web.Compilation.BuildManager.ReportTopLevelCompilationException() +76
   System.Web.Compilation.BuildManager.EnsureTopLevelFilesCompiled() +1012
   System.Web.Hosting.HostingEnvironment.Initialize(ApplicationManager appManager, IApplicationHost appHost, IConfigMapPathFactory configMapPathFactory, HostingEnvironmentParameters hostingParameters) +1025

[HttpException (0x80004005): Could not load file or assembly 'FileHelpers, Version=1.6.0.0, Culture=neutral, PublicKeyToken=null' or one of its dependencies. Failed to grant minimum permission requests. (Exception from HRESULT: 0x80131417)]
   System.Web.HttpRuntime.FirstRequestInit(HttpContext context) +11301302
   System.Web.HttpRuntime.EnsureFirstRequestInit(HttpContext context) +88
   System.Web.HttpRuntime.ProcessRequestNotificationPrivate(IIS7WorkerRequest wr, HttpContext context) +4338644

Sort of a stab in the dark here, but try three things:

• In IIS manager, find the application pool that your application is running under and open up the advanced settings. Make sure the Enable 32 bit applicaitons" setting is true.

• Make sure you are running Visual Studio as an administrator.

• Check the references in solution explorer for your sub-projects. Try setting the "copy local" property on reference for the FileHelpers to false. You'll probably need to add a reference to this assembly directly in your web project, and there you'd leave copy local set to true. (I've seen cases where two sub-projects trying to push in the same referenced DLLs to a single web app can cause interesting side-effects). Also make sure both sub-projects reference the EXACT same FileHelpers assembly from the same physical location.

Try this: load up the .NET Configuration wizard/tool (start > control panel > Administrative Tools > .NET Configuration)

click on Runtime Security Policies

Select "Adjust Zone Security" in the right handside panel..

It's also common to get that problem if you are loading DLL's that are not located on the local harddrive.. If the files are on a fileserver etc, move it to C: somewhere..

the problem disappeared after I reinstalled windows, IIS, VS, so I don't really now why I had this problem