Blazor Server-side: New Template for preview 4 first load server exception

Newly created Blazor server side throws a server exception on first page load.

Just created a new Blazor server-side project from the templates. On first run it throws an exception when it attempts to connect to SignalR making the page non interactive since it only shows the prerendered content.

The exception is due to a Type mismatch for System.Text.Json.Utf8JsonWriter which is shown on the network tab for the browser.

To Reproduce

Steps to reproduce the behavior:

1. Using this version of ASP.NET Core ‘3.0.0-preview5-27618-16’
2. Using Visual Studio 2019 16.1 preview
3. Create a new Blazor Server-side (Still named Razor Components) template
4. Run the created template via F5

Expected behavior

Page will become interactive after prerendering and no 500 internal server errors on browser network tab.

Additional context

Here’s the stack trace given on the network tab.

System.TypeLoadException: Could not load type 'System.Text.Json.Utf8JsonWriter' from assembly 'Microsoft.AspNetCore.Http.Connections.Common, Version=3.0.0.0, Culture=neutral, PublicKeyToken=adb9793829ddae60' due to value type mismatch.
   at Microsoft.AspNetCore.Http.Connections.NegotiateProtocol.WriteResponse(NegotiationResponse response, IBufferWriter`1 output)
   at Microsoft.AspNetCore.Http.Connections.Internal.HttpConnectionDispatcher.WriteNegotiatePayload(IBufferWriter`1 writer, String connectionId, HttpContext context, HttpConnectionDispatcherOptions options)
   at Microsoft.AspNetCore.Http.Connections.Internal.HttpConnectionDispatcher.ProcessNegotiate(HttpContext context, HttpConnectionDispatcherOptions options, ConnectionLogScope logScope)
   at Microsoft.AspNetCore.Http.Connections.Internal.HttpConnectionDispatcher.ExecuteNegotiateAsync(HttpContext context, HttpConnectionDispatcherOptions options)
   at Microsoft.AspNetCore.Routing.EndpointMiddleware.<Invoke>g__AwaitRequestTask|6_0(Endpoint endpoint, Task requestTask, ILogger logger)
   at Microsoft.AspNetCore.Diagnostics.DeveloperExceptionPageMiddleware.Invoke(HttpContext context)

HEADERS
=======
Accept: */*
Accept-Encoding: gzip, deflate, br
Accept-Language: en-US,en;q=0.9
Cache-Control: no-cache
Connection: close
Content-Length: 0
Content-Type: text/plain;charset=UTF-8
Host: localhost:44398
Pragma: no-cache
Referer: https://localhost:44398/
User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/73.0.3683.103 Safari/537.36
origin: https://localhost:44398
x-requested-with: XMLHttpRequest

[BrennanConroy]

3.0.100-preview5-011498 didn’t have the fix, but the next one did. So 3.0.100-preview5-011504 works.

[davidfowl]

The new build works now