Reference assemblies should not be loaded for execution

Question

All of a sudden my website is throwing this error message when I try to debug it within Visual Studio. If I deploy the website, it works without any errors.

Any suggestions to resolve this error.

[ConfigurationErrorsException: Could not load file or assembly 'Microsoft.Win32.Primitives' or one of its dependencies. Reference assemblies should not be loaded for execution.  They can only be loaded in the Reflection-only loader context. (Exception from HRESULT: 0x80131058)]
   System.Web.Configuration.CompilationSection.LoadAssemblyHelper(String assemblyName, Boolean starDirective) +738
   System.Web.Configuration.CompilationSection.LoadAllAssembliesFromAppDomainBinDirectory() +217
   System.Web.Configuration.CompilationSection.LoadAssembly(AssemblyInfo ai) +130
   System.Web.Compilation.BuildManager.GetReferencedAssemblies(CompilationSection compConfig) +170
   System.Web.Compilation.BuildManager.GetPreStartInitMethodsFromReferencedAssemblies() +92
   System.Web.Compilation.BuildManager.CallPreStartInitMethods(String preStartInitListPath, Boolean& isRefAssemblyLoaded) +290
   System.Web.Compilation.BuildManager.ExecutePreAppStart() +157
   System.Web.Hosting.HostingEnvironment.Initialize(ApplicationManager appManager, IApplicationHost appHost, IConfigMapPathFactory configMapPathFactory, HostingEnvironmentParameters hostingParameters, PolicyLevel policyLevel, Exception appDomainCreationException) +531

[HttpException (0x80004005): Could not load file or assembly 'Microsoft.Win32.Primitives' or one of its dependencies. Reference assemblies should not be loaded for execution.  They can only be loaded in the Reflection-only loader context. (Exception from HRESULT: 0x80131058)]
   System.Web.HttpRuntime.FirstRequestInit(HttpContext context) +9946132
   System.Web.HttpRuntime.EnsureFirstRequestInit(HttpContext context) +90
   System.Web.HttpRuntime.ProcessRequestNotificationPrivate(IIS7WorkerRequest wr, HttpContext context) +261

Answer 1

Try delete that section from your web.config

<dependentAssembly>
    <assemblyIdentity name="System.Runtime" publicKeyToken="b03f5f7f11d50a3a" culture="neutral" />
    <bindingRedirect oldVersion="0.0.0.0-4.0.10.0" newVersion="4.0.10.0" />
  </dependentAssembly>

Answer 2

I had this problem, but with System.Runtime specified in the error message:

[BadImageFormatException: Could not load file or assembly 'System.Runtime' or one of its dependencies. Reference assemblies should not be loaded for execution.  They can only be loaded in the Reflection-only loader context. (Exception from HRESULT: 0x80131058)]

I found that thoroughly cleaning the solution and rebuilding fixed this problem for me. And just doing a Visual Studio Clean wasn't enough. I actually had to delete my \bin folders as well.

Answer 3

Delete the \bin directory, Rebuild your project.

Answer 4

If you are working with .NET Core, and have this:

using System.Data.SqlClient;

Then, switching it to this is a potential solution:

using Microsoft.Data.SqlClient;