aspnetcore: Spa Service Showing 503 Service Unavailable page with AspNetCore 3.0 and 3.1

I am recreating this issue: https://github.com/dotnet/aspnetcore/issues/19132#issue-567285637 since it was closed because a new version of SPA project templates might resolve the issue, but it continues exactly the same.

Describe the bug

When running a project with AspNetCore.SpaServices and AspNetCore 3.0 or 3.1 I get a “503 Service Unavailable” page. This only happens with the SPA page, the api (/WeatherForecast) still responds. I first noticed this migrating a project from AspNetCore 2.2 to 3.0. The same error occurs when I create a project from a template in visual studio. I have tested with AspNetCore 3.0 and 3.1, React and Angular templates, running with IISExpress and with project name, with and without https, all cases have the same error. If I publish the project and run the .exe in the publish folder, the error does not happen and page is displayed normally. This is happening on two machines, one windows 10 professional and one windows 7.

To Reproduce

Open Visual Studio
Create new project
Select React Template
Run with F5
Page with 503 Service Unavailable opens

Further technical details

ASP.NET Core version 3.1
Include the output of dotnet --info

.NET Core SDK (reflecting any global.json): Version: 3.1.201 Commit: b1768b4ae7

Runtime Environment: OS Name: Windows OS Version: 10.0.17763 OS Platform: Windows RID: win10-x64 Base Path: C:\Program Files\dotnet\sdk\3.1.201\

Host (useful for support): Version: 3.1.3 Commit: 4a9f85e9f8

.NET Core SDKs installed: 2.1.202 [C:\Program Files\dotnet\sdk] 2.1.504 [C:\Program Files\dotnet\sdk] 2.1.505 [C:\Program Files\dotnet\sdk] 2.1.507 [C:\Program Files\dotnet\sdk] 2.1.508 [C:\Program Files\dotnet\sdk] 2.1.509 [C:\Program Files\dotnet\sdk] 2.1.511 [C:\Program Files\dotnet\sdk] 2.1.513 [C:\Program Files\dotnet\sdk] 2.2.104 [C:\Program Files\dotnet\sdk] 3.1.101 [C:\Program Files\dotnet\sdk] 3.1.201 [C:\Program Files\dotnet\sdk]

.NET Core runtimes installed: Microsoft.AspNetCore.All 2.1.8 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.All] Microsoft.AspNetCore.All 2.1.9 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.All] Microsoft.AspNetCore.All 2.1.11 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.All] Microsoft.AspNetCore.All 2.1.12 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.All] Microsoft.AspNetCore.All 2.1.13 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.All] Microsoft.AspNetCore.All 2.1.15 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.All] Microsoft.AspNetCore.All 2.1.17 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.All] Microsoft.AspNetCore.All 2.2.2 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.All] Microsoft.AspNetCore.App 2.1.8 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App] Microsoft.AspNetCore.App 2.1.9 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App] Microsoft.AspNetCore.App 2.1.11 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App] Microsoft.AspNetCore.App 2.1.12 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App] Microsoft.AspNetCore.App 2.1.13 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App] Microsoft.AspNetCore.App 2.1.15 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App] Microsoft.AspNetCore.App 2.1.17 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App] Microsoft.AspNetCore.App 2.2.2 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App] Microsoft.AspNetCore.App 3.1.1 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App] Microsoft.AspNetCore.App 3.1.3 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App] Microsoft.NETCore.App 2.0.9 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App] Microsoft.NETCore.App 2.1.8 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App] Microsoft.NETCore.App 2.1.9 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App] Microsoft.NETCore.App 2.1.11 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App] Microsoft.NETCore.App 2.1.12 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App] Microsoft.NETCore.App 2.1.13 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App] Microsoft.NETCore.App 2.1.15 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App] Microsoft.NETCore.App 2.1.17 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App] Microsoft.NETCore.App 2.2.2 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App] Microsoft.NETCore.App 3.1.1 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App] Microsoft.NETCore.App 3.1.3 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App] Microsoft.WindowsDesktop.App 3.1.1 [C:\Program Files\dotnet\shared\Microsoft.WindowsDesktop.App] Microsoft.WindowsDesktop.App 3.1.3 [C:\Program Files\dotnet\shared\Microsoft.WindowsDesktop.App]

To install additional .NET Core runtimes or SDKs: https://aka.ms/dotnet-download

The IDE (VS / VS Code/ VS4Mac) you’re running on, and it’s version

Microsoft Visual Studio Community 2019 Version 16.5.4 VisualStudio.16.Release/16.5.4+30011.22 Microsoft .NET Framework Version 4.8.03761

Installed Version: Community

Visual C++ 2019 00435-60000-00000-AA593 Microsoft Visual C++ 2019

ADL Tools Service Provider 1.0 This package contains services used by Data Lake tools

ASA Service Provider 1.0

ASP.NET and Web Tools 2019 16.5.236.49856 ASP.NET and Web Tools 2019

ASP.NET Web Frameworks and Tools 2012 16.5.236.49856 For additional information, visit https://www.asp.net/

ASP.NET Web Frameworks and Tools 2019 16.5.236.49856 For additional information, visit https://www.asp.net/

Azure App Service Tools v3.0.0 16.5.236.49856 Azure App Service Tools v3.0.0

Azure Data Lake Node 1.0 This package contains the Data Lake integration nodes for Server Explorer.

Azure Data Lake Tools for Visual Studio 2.4.5000.0 Microsoft Azure Data Lake Tools for Visual Studio

Azure Functions and Web Jobs Tools 16.5.236.49856 Azure Functions and Web Jobs Tools

Azure Stream Analytics Tools for Visual Studio 2.4.5000.0 Microsoft Azure Stream Analytics Tools for Visual Studio

C# Tools 3.5.0-beta4-20153-05+20b9af913f1b8ce0a62f72bea9e75e4aa3cf6b0e C# components used in the IDE. Depending on your project type and settings, a different version of the compiler may be used.

Common Azure Tools 1.10 Provides common services for use by Azure Mobile Services and Microsoft Azure Tools.

IntelliCode Extension 1.0 IntelliCode Visual Studio Extension Detailed Info

Microsoft Azure HDInsight Azure Node 2.4.5000.0 HDInsight Node under Azure Node

Microsoft Azure Hive Query Language Service 2.4.5000.0 Language service for Hive query

Microsoft Azure Stream Analytics Language Service 2.4.5000.0 Language service for Azure Stream Analytics

Microsoft Azure Stream Analytics Node 1.0 Azure Stream Analytics Node under Azure Node

Microsoft Azure Tools 2.9 Microsoft Azure Tools for Microsoft Visual Studio 2019 - v2.9.30207.1

Microsoft Continuous Delivery Tools for Visual Studio 0.4 Simplifying the configuration of Azure DevOps pipelines from within the Visual Studio IDE.

Microsoft JVM Debugger 1.0 Provides support for connecting the Visual Studio debugger to JDWP compatible Java Virtual Machines

Microsoft Library Manager 2.1.25+gdacdb9b7a1 Install client-side libraries easily to any web project

Microsoft MI-Based Debugger 1.0 Provides support for connecting Visual Studio to MI compatible debuggers

Microsoft Visual C++ Wizards 1.0 Microsoft Visual C++ Wizards

Microsoft Visual Studio Tools for Containers 1.1 Develop, run, validate your ASP.NET Core applications in the target environment. F5 your application directly into a container with debugging, or CTRL + F5 to edit & refresh your app without having to rebuild the container.

Microsoft Visual Studio VC Package 1.0 Microsoft Visual Studio VC Package

Node.js Tools 1.5.20122.1 Commit Hash:d74ac73e6e22f9e009948cab4535a26194b19b1b Adds support for developing and debugging Node.js apps in Visual Studio

NuGet Package Manager 5.5.0 NuGet Package Manager in Visual Studio. For more information about NuGet, visit https://docs.nuget.org/

ProjectServicesPackage Extension 1.0 ProjectServicesPackage Visual Studio Extension Detailed Info

SQL Server Data Tools 16.0.62003.05170 Microsoft SQL Server Data Tools

ToolWindowHostedEditor 1.0 Hosting json editor into a tool window

TypeScript Tools 16.0.20225.2001 TypeScript Tools for Microsoft Visual Studio

Visual Basic Tools 3.5.0-beta4-20153-05+20b9af913f1b8ce0a62f72bea9e75e4aa3cf6b0e Visual Basic components used in the IDE. Depending on your project type and settings, a different version of the compiler may be used.

Visual F# Tools 10.8.0.0 for F# 4.7 16.5.0-beta.20181.6+85af456066acd4e76d2bc7821b44a325e46f2fca Microsoft Visual F# Tools 10.8.0.0 for F# 4.7

Visual Studio Code Debug Adapter Host Package 1.0 Interop layer for hosting Visual Studio Code debug adapters in Visual Studio

Visual Studio Container Tools Extensions (Preview) 1.0 View, manage, and diagnose containers within Visual Studio.

Visual Studio Tools for Containers 1.0 Visual Studio Tools for Containers

Log with trace:

info: Microsoft.Hosting.Lifetime[0]
      Now listening on: https://localhost:5001
info: Microsoft.Hosting.Lifetime[0]
      Now listening on: http://localhost:5000
info: Microsoft.Hosting.Lifetime[0]
      Application started. Press Ctrl+C to shut down.
info: Microsoft.Hosting.Lifetime[0]
      Hosting environment: Development
info: Microsoft.Hosting.Lifetime[0]
      Content root path: D:\source\repos\WebApplication4\WebApplication4
info: Microsoft.Hosting.Lifetime[0]
      Application is shutting down...
dbug: Microsoft.Extensions.Hosting.Internal.Host[1]
      Hosting starting
info: Microsoft.AspNetCore.DataProtection.KeyManagement.XmlKeyManager[0]
      User profile is available. Using 'C:\Users\faria\AppData\Local\ASP.NET\DataProtection-Keys' as key repository and Windows DPAPI to encrypt keys at rest.
dbug: Microsoft.AspNetCore.DataProtection.Repositories.FileSystemXmlRepository[37]
      Reading data from file 'C:\Users\faria\AppData\Local\ASP.NET\DataProtection-Keys\key-07ad0de7-3e52-42a1-925c-68f562437714.xml'.
dbug: Microsoft.AspNetCore.DataProtection.Repositories.FileSystemXmlRepository[37]
      Reading data from file 'C:\Users\faria\AppData\Local\ASP.NET\DataProtection-Keys\key-49669963-ddfc-49b6-903c-c774f3733270.xml'.
dbug: Microsoft.AspNetCore.DataProtection.Repositories.FileSystemXmlRepository[37]
      Reading data from file 'C:\Users\faria\AppData\Local\ASP.NET\DataProtection-Keys\key-acc9296a-c40c-4b56-9fdc-34050fe40c04.xml'.
dbug: Microsoft.AspNetCore.DataProtection.Repositories.FileSystemXmlRepository[37]
      Reading data from file 'C:\Users\faria\AppData\Local\ASP.NET\DataProtection-Keys\key-c436709c-03a9-4552-83ce-ff4d9f9c2172.xml'.
dbug: Microsoft.AspNetCore.DataProtection.Repositories.FileSystemXmlRepository[37]
      Reading data from file 'C:\Users\faria\AppData\Local\ASP.NET\DataProtection-Keys\key-e899ecaf-9efc-4b32-bf48-d48919450097.xml'.
dbug: Microsoft.AspNetCore.DataProtection.KeyManagement.XmlKeyManager[18]
      Found key {07ad0de7-3e52-42a1-925c-68f562437714}.
dbug: Microsoft.AspNetCore.DataProtection.KeyManagement.XmlKeyManager[18]
      Found key {49669963-ddfc-49b6-903c-c774f3733270}.
dbug: Microsoft.AspNetCore.DataProtection.KeyManagement.XmlKeyManager[18]
      Found key {acc9296a-c40c-4b56-9fdc-34050fe40c04}.
dbug: Microsoft.AspNetCore.DataProtection.KeyManagement.XmlKeyManager[18]
      Found key {c436709c-03a9-4552-83ce-ff4d9f9c2172}.
dbug: Microsoft.AspNetCore.DataProtection.KeyManagement.XmlKeyManager[18]
      Found key {e899ecaf-9efc-4b32-bf48-d48919450097}.
dbug: Microsoft.AspNetCore.DataProtection.KeyManagement.DefaultKeyResolver[13]
      Considering key {e899ecaf-9efc-4b32-bf48-d48919450097} with expiration date 2020-07-29 17:57:47Z as default key.
dbug: Microsoft.AspNetCore.DataProtection.TypeForwardingActivator[0]
      Forwarded activator type request from Microsoft.AspNetCore.DataProtection.XmlEncryption.DpapiXmlDecryptor, Microsoft.AspNetCore.DataProtection, Version=2.2.0.0, Culture=neutral, PublicKeyToken=adb9793829ddae60 to Microsoft.AspNetCore.DataProtection.XmlEncryption.DpapiXmlDecryptor, Microsoft.AspNetCore.DataProtection, Culture=neutral, PublicKeyToken=adb9793829ddae60
dbug: Microsoft.AspNetCore.DataProtection.XmlEncryption.DpapiXmlDecryptor[51]
      Decrypting secret element using Windows DPAPI.
dbug: Microsoft.AspNetCore.DataProtection.TypeForwardingActivator[0]
      Forwarded activator type request from Microsoft.AspNetCore.DataProtection.AuthenticatedEncryption.ConfigurationModel.AuthenticatedEncryptorDescriptorDeserializer, Microsoft.AspNetCore.DataProtection, Version=2.2.0.0, Culture=neutral, PublicKeyToken=adb9793829ddae60 to Microsoft.AspNetCore.DataProtection.AuthenticatedEncryption.ConfigurationModel.AuthenticatedEncryptorDescriptorDeserializer, Microsoft.AspNetCore.DataProtection, Culture=neutral, PublicKeyToken=adb9793829ddae60
dbug: Microsoft.AspNetCore.DataProtection.AuthenticatedEncryption.CngCbcAuthenticatedEncryptorFactory[4]
      Opening CNG algorithm 'AES' from provider '(null)' with chaining mode CBC.
dbug: Microsoft.AspNetCore.DataProtection.AuthenticatedEncryption.CngCbcAuthenticatedEncryptorFactory[3]
      Opening CNG algorithm 'SHA256' from provider '(null)' with HMAC.
dbug: Microsoft.AspNetCore.DataProtection.KeyManagement.KeyRingProvider[2]
      Using key {e899ecaf-9efc-4b32-bf48-d48919450097} as the default key.
dbug: Microsoft.AspNetCore.DataProtection.Internal.DataProtectionHostedService[0]
      Key ring with default key {e899ecaf-9efc-4b32-bf48-d48919450097} was loaded during application startup.
info: Microsoft.AspNetCore.SpaServices[0]
      Starting create-react-app server on port 61646...
dbug: Microsoft.AspNetCore.Server.Kestrel.Core.KestrelServer[2]
      Failed to locate the development https certificate at '(null)'.
dbug: Microsoft.AspNetCore.Server.Kestrel.Core.KestrelServer[0]
      Using development certificate: CN=localhost (Thumbprint: ABC78421FBCEF478AEC1FF5129FF46704DF9AE82)
info: Microsoft.Hosting.Lifetime[0]
      Now listening on: https://localhost:5001
info: Microsoft.Hosting.Lifetime[0]
      Now listening on: http://localhost:5000
dbug: Microsoft.AspNetCore.Hosting.Diagnostics[0]
      Loaded hosting startup assembly WebApplication4
info: Microsoft.Hosting.Lifetime[0]
      Application started. Press Ctrl+C to shut down.
info: Microsoft.Hosting.Lifetime[0]
      Hosting environment: Development
info: Microsoft.Hosting.Lifetime[0]
      Content root path: D:\source\repos\WebApplication4\WebApplication4
dbug: Microsoft.Extensions.Hosting.Internal.Host[2]
      Hosting started
dbug: Microsoft.AspNetCore.Server.Kestrel[39]
      Connection id "0HLVHPJKTO4AI" accepted.
dbug: Microsoft.AspNetCore.Server.Kestrel[39]
      Connection id "0HLVHPJKTO4AJ" accepted.
dbug: Microsoft.AspNetCore.Server.Kestrel[1]
      Connection id "0HLVHPJKTO4AJ" started.
dbug: Microsoft.AspNetCore.Server.Kestrel[1]
      Connection id "0HLVHPJKTO4AI" started.
dbug: Microsoft.AspNetCore.Server.Kestrel.Transport.Sockets[6]
      Connection id "0HLVHPJKTO4AJ" received FIN.
dbug: Microsoft.AspNetCore.Server.Kestrel.Transport.Sockets[6]
      Connection id "0HLVHPJKTO4AI" received FIN.
dbug: Microsoft.AspNetCore.Server.Kestrel.Https.Internal.HttpsConnectionMiddleware[1]
      Failed to authenticate HTTPS connection.
System.IO.IOException: Authentication failed because the remote party has closed the transport stream.
   at System.Net.Security.SslStream.StartReadFrame(Byte[] buffer, Int32 readBytes, AsyncProtocolRequest asyncRequest)
   at System.Net.Security.SslStream.PartialFrameCallback(AsyncProtocolRequest asyncRequest)
--- End of stack trace from previous location where exception was thrown ---
   at System.Net.Security.SslStream.ThrowIfExceptional()
   at System.Net.Security.SslStream.InternalEndProcessAuthentication(LazyAsyncResult lazyResult)
   at System.Net.Security.SslStream.EndProcessAuthentication(IAsyncResult result)
   at System.Net.Security.SslStream.EndAuthenticateAsServer(IAsyncResult asyncResult)
   at System.Net.Security.SslStream.<>c.<AuthenticateAsServerAsync>b__69_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.HttpsConnectionMiddleware.InnerOnConnectionAsync(ConnectionContext context)
dbug: Microsoft.AspNetCore.Server.Kestrel.Https.Internal.HttpsConnectionMiddleware[1]
      Failed to authenticate HTTPS connection.
System.IO.IOException: Authentication failed because the remote party has closed the transport stream.
   at System.Net.Security.SslStream.StartReadFrame(Byte[] buffer, Int32 readBytes, AsyncProtocolRequest asyncRequest)
   at System.Net.Security.SslStream.PartialFrameCallback(AsyncProtocolRequest asyncRequest)
--- End of stack trace from previous location where exception was thrown ---
   at System.Net.Security.SslStream.ThrowIfExceptional()
   at System.Net.Security.SslStream.InternalEndProcessAuthentication(LazyAsyncResult lazyResult)
   at System.Net.Security.SslStream.EndProcessAuthentication(IAsyncResult result)
   at System.Net.Security.SslStream.EndAuthenticateAsServer(IAsyncResult asyncResult)
   at System.Net.Security.SslStream.<>c.<AuthenticateAsServerAsync>b__69_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.HttpsConnectionMiddleware.InnerOnConnectionAsync(ConnectionContext context)
dbug: Microsoft.AspNetCore.Server.Kestrel[2]
      Connection id "0HLVHPJKTO4AJ" stopped.
dbug: Microsoft.AspNetCore.Server.Kestrel[2]
      Connection id "0HLVHPJKTO4AI" stopped.
dbug: Microsoft.AspNetCore.Server.Kestrel.Transport.Sockets[7]
      Connection id "0HLVHPJKTO4AJ" sending FIN because: "The Socket transport's send loop completed gracefully."
dbug: Microsoft.AspNetCore.Server.Kestrel.Transport.Sockets[7]
      Connection id "0HLVHPJKTO4AI" sending FIN because: "The Socket transport's send loop completed gracefully."
dbug: Microsoft.AspNetCore.Server.Kestrel[39]
      Connection id "0HLVHPJKTO4AK" accepted.
dbug: Microsoft.AspNetCore.Server.Kestrel[1]
      Connection id "0HLVHPJKTO4AK" started.
trce: Microsoft.AspNetCore.Server.Kestrel[37]
      Connection id "0HLVHPJKTO4AK" sending SETTINGS frame for stream ID 0 with length 18 and flags NONE
trce: Microsoft.AspNetCore.Server.Kestrel[37]
      Connection id "0HLVHPJKTO4AK" sending WINDOW_UPDATE frame for stream ID 0 with length 4 and flags 0x0
trce: Microsoft.AspNetCore.Server.Kestrel[37]
      Connection id "0HLVHPJKTO4AK" received SETTINGS frame for stream ID 0 with length 24 and flags NONE
trce: Microsoft.AspNetCore.Server.Kestrel[37]
      Connection id "0HLVHPJKTO4AK" sending SETTINGS frame for stream ID 0 with length 0 and flags ACK
trce: Microsoft.AspNetCore.Server.Kestrel[37]
      Connection id "0HLVHPJKTO4AK" received WINDOW_UPDATE frame for stream ID 0 with length 4 and flags 0x0
trce: Microsoft.AspNetCore.Server.Kestrel[37]
      Connection id "0HLVHPJKTO4AK" received HEADERS frame for stream ID 1 with length 395 and flags END_STREAM, END_HEADERS, PRIORITY
trce: Microsoft.AspNetCore.Server.Kestrel[37]
      Connection id "0HLVHPJKTO4AK" received SETTINGS frame for stream ID 0 with length 0 and flags ACK
info: Microsoft.AspNetCore.Hosting.Diagnostics[1]
      Request starting HTTP/2 GET https://localhost:5001/  
dbug: Microsoft.AspNetCore.HostFiltering.HostFilteringMiddleware[0]
      Wildcard detected, all requests with hosts will be allowed.
trce: Microsoft.AspNetCore.HostFiltering.HostFilteringMiddleware[2]
      All hosts are allowed.
dbug: Microsoft.AspNetCore.StaticFiles.StaticFileMiddleware[4]
      The request path / does not match a supported file type
dbug: Microsoft.AspNetCore.Routing.Matching.DfaMatcher[1000]
      No candidates found for the request path '/'
dbug: Microsoft.AspNetCore.Routing.EndpointRoutingMiddleware[2]
      Request did not match any endpoints
info: Microsoft.AspNetCore.SpaServices[0]
      > webapplication4@0.1.0 start D:\source\repos\WebApplication4\WebApplication4\ClientApp
> rimraf ./build && react-scripts start

i ｢wds｣: Project is running at http://192.168.4.86/

info: Microsoft.AspNetCore.SpaServices[0]
      i ｢wds｣: webpack output is served from 

info: Microsoft.AspNetCore.SpaServices[0]
      i ｢wds｣: Content not from webpack is served from D:\source\repos\WebApplication4\WebApplication4\ClientApp\public
i ｢wds｣: 404s will fallback to /
Starting the development server...

Compiled successfully!

trce: Microsoft.AspNetCore.Server.Kestrel[37]
      Connection id "0HLVHPJKTO4AK" sending HEADERS frame for stream ID 1 with length 156 and flags END_HEADERS
trce: Microsoft.AspNetCore.Server.Kestrel[37]
      Connection id "0HLVHPJKTO4AK" sending DATA frame for stream ID 1 with length 133 and flags NONE
trce: Microsoft.AspNetCore.Server.Kestrel[37]
      Connection id "0HLVHPJKTO4AK" sending DATA frame for stream ID 1 with length 0 and flags END_STREAM
info: Microsoft.AspNetCore.Hosting.Diagnostics[2]
      Request finished in 4065.4414ms 503 text/html; charset=UTF-8
trce: Microsoft.AspNetCore.Server.Kestrel[37]
      Connection id "0HLVHPJKTO4AK" received HEADERS frame for stream ID 3 with length 104 and flags END_STREAM, END_HEADERS, PRIORITY
info: Microsoft.AspNetCore.Hosting.Diagnostics[1]
      Request starting HTTP/2 GET https://localhost:5001/favicon.ico  
trce: Microsoft.AspNetCore.HostFiltering.HostFilteringMiddleware[2]
      All hosts are allowed.
dbug: Microsoft.AspNetCore.StaticFiles.StaticFileMiddleware[5]
      The request path /favicon.ico does not match an existing file
dbug: Microsoft.AspNetCore.Routing.Matching.DfaMatcher[1000]
      No candidates found for the request path '/favicon.ico'
dbug: Microsoft.AspNetCore.Routing.EndpointRoutingMiddleware[2]
      Request did not match any endpoints
trce: Microsoft.AspNetCore.Server.Kestrel[37]
      Connection id "0HLVHPJKTO4AK" sending HEADERS frame for stream ID 3 with length 156 and flags END_HEADERS
trce: Microsoft.AspNetCore.Server.Kestrel[37]
      Connection id "0HLVHPJKTO4AK" sending DATA frame for stream ID 3 with length 133 and flags NONE
trce: Microsoft.AspNetCore.Server.Kestrel[37]
      Connection id "0HLVHPJKTO4AK" sending DATA frame for stream ID 3 with length 0 and flags END_STREAM
info: Microsoft.AspNetCore.Hosting.Diagnostics[2]
      Request finished in 31.1017ms 503 text/html; charset=UTF-8

aspnetcore: Spa Service Showing 503 Service Unavailable page with AspNetCore 3.0 and 3.1

Describe the bug

To Reproduce

Further technical details

About this issue

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