Could not load file or assembly 'Elmish, Version=4.0.1.0, Culture=neutral, PublicKeyToken=null'

[alfbostefan]

It seems that I have a similar problem as the issue 180,

Doing this will trigger my error:

dotnet new install Bolero.Templates
dotnet new bolero-app -o Test
cd Test
dotnet run --project src/Test.Server

Navigation to http://127.0.0.1:5000 will trigger this error:

Now listening on: http://localhost:5000
Application started. Press Ctrl+C to shut down.
info: Microsoft.AspNetCore.Hosting.Diagnostics[1]
      Request starting HTTP/1.1 GET http://127.0.0.1:5000/ - -
info: Microsoft.AspNetCore.Routing.EndpointMiddleware[0]
      Executing endpoint 'Fallback {*path:nonfile}'     
info: Microsoft.AspNetCore.Routing.EndpointMiddleware[1]
      Executed endpoint 'Fallback {*path:nonfile}'      
fail: Microsoft.AspNetCore.Server.Kestrel[13]
      Connection id "0HMPSTF03GJD6", Request id "0HMPSTF03GJD6:00000001": An unhandled exception was thrown by the application.
      System.IO.FileNotFoundException: Could not load file or assembly 'Elmish, Version=4.0.1.0, Culture=neutral, PublicKeyToken=null'. The system cannot find the file specified.
      File name: 'Elmish, Version=4.0.1.0, Culture=neutral, PublicKeyToken=null'
         at Test.Client.Main.MyApp.get_Program()
         at Bolero.ProgramComponent`2.OnInitialized()
         at Microsoft.AspNetCore.Components.ComponentBase.RunInitAndSetParametersAsync()
         at Microsoft.AspNetCore.Components.Rendering.ComponentState.SetDirectParameters(ParameterView parameters)
         at Microsoft.AspNetCore.Components.RenderTree.Renderer.RenderRootComponentAsync(Int32 componentId, ParameterView initialParameters)
         at Microsoft.AspNetCore.Components.Rendering.HtmlRenderer.RenderComponentAsync(Type componentType, ParameterView initialParameters)
         at Microsoft.AspNetCore.Components.Rendering.RendererSynchronizationContext.<>c__11`1.<<InvokeAsync>b__11_0>d.MoveNext()
      --- End of stack trace from previous location ---
         at Microsoft.AspNetCore.Mvc.ViewFeatures.StaticComponentRenderer.PrerenderComponentAsync(ParameterView parameters, HttpContext httpContext, Type componentType)
         at Microsoft.AspNetCore.Mvc.ViewFeatures.ComponentRenderer.RenderComponentAsync(ViewContext viewContext, Type componentType, RenderMode renderMode, Object parameters)
         at Microsoft.AspNetCore.Mvc.Rendering.HtmlHelperComponentExtensions.RenderComponentAsync(IHtmlHelper htmlHelper, Type componentType, RenderMode renderMode, Object parameters)
         at Bolero.Server.Components.Rendering.renderCompTo@81.MoveNext()
         at Bolero.Server.Components.Rendering.renderPage@183.Bolero.Server.Components.Rendering.IRenderComponents.RenderComponent(Type ty, StringBuilder sb, IDictionary`2 attributes, Boolean forceStatic)      
         at Bolero.Server.Components.Rendering.render(IRenderComponents renderComp, ReadOnlySpan`1 frames, RenderState state, StringBuilder sb)
         at Bolero.Server.Components.Rendering.render(IRenderComponents renderComp, ReadOnlySpan`1 frames, RenderState state, StringBuilder sb)
         at Bolero.Server.Components.Rendering.render(IRenderComponents renderComp, ReadOnlySpan`1 frames, RenderState state, StringBuilder sb)
         at Bolero.Server.Components.Rendering.render(IRenderComponents renderComp, ReadOnlySpan`1 frames, RenderState state, StringBuilder sb)
         at Bolero.Server.Components.Rendering.renderWith(IRenderComponents renderComp, Node node)
         at Bolero.Server.Components.Rendering.renderPage(Node page, HttpContext httpContext, IHtmlHelper htmlHelper, IBoleroHostConfig boleroConfig)
         at <StartupCode$Bolero-Server>.$Extensions.RenderPage@61.MoveNext()
         at Microsoft.AspNetCore.Routing.EndpointMiddleware.<Invoke>g__AwaitRequestTask|6_0(Endpoint endpoint, Task requestTask, ILogger logger)
         at Microsoft.AspNetCore.Authorization.AuthorizationMiddleware.Invoke(HttpContext context)
         at Microsoft.AspNetCore.Authentication.AuthenticationMiddleware.Invoke(HttpContext context)
         at Microsoft.AspNetCore.Server.Kestrel.Core.Internal.Http.HttpProtocol.ProcessRequests[TContext](IHttpApplication`1 application)
info: Microsoft.AspNetCore.Hosting.Diagnostics[2]
      Request finished HTTP/1.1 GET http://127.0.0.1:5000/ - - - 500 0 - 195.9606ms

This is my dotnet-info:

 dotnet --info
.NET SDK:
 Version:   7.0.300-preview.23179.2
 Commit:    6d2b42e30e

Runtime Environment:
 OS Name:     Windows
 OS Version:  10.0.19044
 OS Platform: Windows
 RID:         win10-x64
 Base Path:   C:\Program Files\dotnet\sdk\7.0.300-preview.23179.2\

Host:
  Version:      7.0.5
  Architecture: x64
  Commit:       8042d61b17

.NET SDKs installed:
  6.0.201 [C:\Program Files\dotnet\sdk]
  7.0.203 [C:\Program Files\dotnet\sdk]
  7.0.300-preview.23179.2 [C:\Program Files\dotnet\sdk]

.NET runtimes installed:
  Microsoft.AspNetCore.App 6.0.3 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
  Microsoft.AspNetCore.App 6.0.15 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
  Microsoft.AspNetCore.App 7.0.4 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
  Microsoft.AspNetCore.App 7.0.5 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
  Microsoft.NETCore.App 6.0.3 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
  Microsoft.NETCore.App 6.0.15 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
  Microsoft.NETCore.App 7.0.4 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
  Microsoft.NETCore.App 7.0.5 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
  Microsoft.WindowsDesktop.App 6.0.3 [C:\Program Files\dotnet\shared\Microsoft.WindowsDesktop.App]
  Microsoft.WindowsDesktop.App 6.0.15 [C:\Program Files\dotnet\shared\Microsoft.WindowsDesktop.App]
  Microsoft.WindowsDesktop.App 7.0.4 [C:\Program Files\dotnet\shared\Microsoft.WindowsDesktop.App]
  Microsoft.WindowsDesktop.App 7.0.5 [C:\Program Files\dotnet\shared\Microsoft.WindowsDesktop.App]

Other architectures found:
  x86   [C:\Program Files (x86)\dotnet]
    registered at [HKLM\SOFTWARE\dotnet\Setup\InstalledVersions\x86\InstallLocation]

Environment variables:
  Not set

global.json file:
  Not found

Learn more:
  https://aka.ms/dotnet/info

Download .NET:
  https://aka.ms/dotnet/download

If I explicit add the 4.0.1 version of Elmish to the project it will work as expected. Let me know if there are any more information needed from me.

[Tarmil]

I think I see what's going on; due to some subtle package resolution hijinks, Bolero.HotReload.dll references Elmish.dll 4.0.1 even though the Bolero.HotReload package requires only the Elmish package >= 4.0.0. Adding an explicit Elmish package version will indeed work around the issue in your project.

It should possible to fix the root cause by tweaking the version constraints in Bolero.HotReload.

[Tarmil]

The newly released Bolero 0.22.43 and Bolero.HotReload 0.22.6 should solve this issue.

[stefanalfbo]

Yes indeed, works great now. Thanks for the fast response!