ASP.NET Web API – FileNotFoundException: Could not load file or assembly - asp.net

Question

I am using Visual Studio for Mac [Community] Version 8.2.3 on macOS Mojave (10.14.6).
I created a ASP.NET Core API Solution. I need to access a third party DLL and added it to my Project -- it shows up under Dependencies/Assemblies. I am accessing it within a POST method.
Project builds fine. I get the following error when I run in Debug mode and access the POST URL:
$ dotnet run
Using launch settings from /Users/vishal/Projects/Triceratops/Properties/launchSettings.json...
: Microsoft.AspNetCore.DataProtection.KeyManagement.XmlKeyManager[0]
User profile is available. Using '/Users/vishal/.aspnet/DataProtection-Keys' as key repository; keys will not be encrypted at rest.
Hosting environment: Development
Content root path: /Users/vishal/Projects/Triceratops
Now listening on: https://localhost:8080
Now listening on: http://localhost:8000
Application started. Press Ctrl+C to shut down.
dbug: HttpsConnectionAdapter[1]
Failed to authenticate HTTPS connection.
System.IO.IOException: Authentication failed because the remote party has closed the transport stream.
at System.Net.Security.SslState.StartReadFrame(Byte[] buffer, Int32 readBytes, AsyncProtocolRequest asyncRequest)
at System.Net.Security.SslState.PartialFrameCallback(AsyncProtocolRequest asyncRequest)
--- End of stack trace from previous location where exception was thrown ---
at System.Net.Security.SslState.ThrowIfExceptional()
at System.Net.Security.SslState.InternalEndProcessAuthentication(LazyAsyncResult lazyResult)
at System.Net.Security.SslState.EndProcessAuthentication(IAsyncResult result)
at System.Net.Security.SslStream.EndAuthenticateAsServer(IAsyncResult asyncResult)
at System.Net.Security.SslStream.<>c.<AuthenticateAsServerAsync>b__51_1(IAsyncResult iar)
at System.Threading.Tasks.TaskFactory`1.FromAsyncCoreLogic(IAsyncResult iar, Func`2 endFunction, Action`1 endAction, Task`1 promise, Boolean requiresSynchronization)
--- End of stack trace from previous location where exception was thrown ---
at Microsoft.AspNetCore.Server.Kestrel.Https.Internal.HttpsConnectionAdapter.InnerOnConnectionAsync(ConnectionAdapterContext context)
info: Microsoft.AspNetCore.Hosting.Internal.WebHost[1]
Request starting HTTP/1.1 POST https://localhost:8080/api/battery application/json 10432
info: Microsoft.AspNetCore.Mvc.Internal.ControllerActionInvoker[3]
Route matched with {action = "Post", controller = "Battery"}. Executing controller action with signature Double[,] Post(BatteryParamModel) on controller Triceratops.Controllers.BatteryController (Triceratops).
info: Microsoft.AspNetCore.Mvc.Internal.ControllerActionInvoker[1]
Executing action method Triceratops.Controllers.BatteryController.Post (Triceratops) - Validation state: Valid
info: Microsoft.AspNetCore.Mvc.Internal.ControllerActionInvoker[2]
Executed action Triceratops.Controllers.BatteryController.Post (Triceratops) in 109.7701ms
fail: Microsoft.AspNetCore.Diagnostics.DeveloperExceptionPageMiddleware[1]
An unhandled exception has occurred while executing the request.
System.BadImageFormatException: Could not load file or assembly 'RenewablesLibrary, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null'. An attempt was made to load a program with an incorrect format.
File name: 'RenewablesLibrary, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null'
at Triceratops.Controllers.BatteryController.Post(BatteryParamModel data)
at lambda_method(Closure , Object , Object[] )
at Microsoft.Extensions.Internal.ObjectMethodExecutor.Execute(Object target, Object[] parameters)
at Microsoft.AspNetCore.Mvc.Internal.ActionMethodExecutor.SyncObjectResultExecutor.Execute(IActionResultTypeMapper mapper, ObjectMethodExecutor executor, Object controller, Object[] arguments)
at Microsoft.AspNetCore.Mvc.Internal.ControllerActionInvoker.InvokeActionMethodAsync()
at Microsoft.AspNetCore.Mvc.Internal.ControllerActionInvoker.InvokeNextActionFilterAsync()
at Microsoft.AspNetCore.Mvc.Internal.ControllerActionInvoker.Rethrow(ActionExecutedContext context)
at Microsoft.AspNetCore.Mvc.Internal.ControllerActionInvoker.Next(State& next, Scope& scope, Object& state, Boolean& isCompleted)
at Microsoft.AspNetCore.Mvc.Internal.ControllerActionInvoker.InvokeInnerFilterAsync()
at Microsoft.AspNetCore.Mvc.Internal.ResourceInvoker.InvokeNextResourceFilter()
at Microsoft.AspNetCore.Mvc.Internal.ResourceInvoker.Rethrow(ResourceExecutedContext context)
at Microsoft.AspNetCore.Mvc.Internal.ResourceInvoker.Next(State& next, Scope& scope, Object& state, Boolean& isCompleted)
at Microsoft.AspNetCore.Mvc.Internal.ResourceInvoker.InvokeFilterPipelineAsync()
at Microsoft.AspNetCore.Mvc.Internal.ResourceInvoker.InvokeAsync()
at Microsoft.AspNetCore.Builder.RouterMiddleware.Invoke(HttpContext httpContext)
at Microsoft.AspNetCore.Diagnostics.DeveloperExceptionPageMiddleware.Invoke(HttpContext context)
info: Microsoft.AspNetCore.Hosting.Internal.WebHost[2]
Request finished in 285.122ms 500 text/html; charset=utf-8
What am I missing/doing wrong?

Answer 1

Try cleaning the solution and rebuild. Sometimes restarting the Visual Studio also clears this type of issue.
If you are using any package manager like nuget to install, see the packages.config file has the assembly added or add the dependent assembly file in config. See the build files in bin has this dll or not.

Answer 2

An attempt was made to load a program with an incorrect format.
User error. Mine.
I should have been using the x64 DLL and was using the x86 DLL instead. That appears to have fixed it.

Answer 3

I have the same error, I wrote in the package manager console dotnet restore and it works for me!