Trying to start web project - Debug - Start new instance - from Visual Studio 2019. It opens the browser at http://localhost:5221/ with the following error message

HTTP Error 500.30 - ANCM In-Process Start Failure

Instructions in the above page suggest the following:

Common causes of this issue:
The application failed to start
The application started but then stopped
The application started but threw an exception during startup
Troubleshooting steps:
Check the system event log for error messages
Enable logging the application process stdout messages
Attach a debugger to the application process and inspect
For more information visit: https://go.microsoft.com/fwlink/?LinkID=2028265

I've checked the Debug Output and the following exception is logged in the Debug Output window:

Microsoft.AspNetCore.Hosting.WebHost: Critical: Application startup exception

System.NullReferenceException: Object reference not set to an instance of an object.
   at Microsoft.AspNetCore.Hosting.WebHostBuilderIISExtensions.<>c__DisplayClass0_0.<UseIIS>b__2(IISServerOptions options)
   at Microsoft.Extensions.Options.ConfigureNamedOptions`1.Configure(String name, TOptions options)
   at Microsoft.Extensions.Options.OptionsFactory`1.Create(String name)
   at Microsoft.Extensions.Options.OptionsManager`1.<>c__DisplayClass5_0.<Get>b__0()
   at System.Lazy`1.ViaFactory(LazyThreadSafetyMode mode)
   at System.Lazy`1.ExecutionAndPublication(LazyHelper executionAndPublication, Boolean useDefaultConstructor)
   at System.Lazy`1.CreateValue()
   at System.Lazy`1.get_Value()
   at Microsoft.Extensions.Options.OptionsCache`1.GetOrAdd(String name, Func`1 createOptions)
   at Microsoft.Extensions.Options.OptionsManager`1.Get(String name)
   at Microsoft.Extensions.Options.OptionsManager`1.get_Value()
   at Microsoft.AspNetCore.Server.IIS.Core.IISHttpServer..ctor(IISNativeApplication nativeApplication, IHostApplicationLifetime applicationLifetime, IAuthenticationSchemeProvider authentication, IOptions`1 options, ILogger`1 logger)
   at System.RuntimeMethodHandle.InvokeMethod(Object target, Object[] arguments, Signature sig, Boolean constructor, Boolean wrapExceptions)
   at System.Reflection.RuntimeConstructorInfo.Invoke(BindingFlags invokeAttr, Binder binder, Object[] parameters, CultureInfo culture)
   at Microsoft.Extensions.DependencyInjection.ServiceLookup.CallSiteRuntimeResolver.VisitConstructor(ConstructorCallSite constructorCallSite, RuntimeResolverContext context)
   at Microsoft.Extensions.DependencyInjection.ServiceLookup.CallSiteVisitor`2.VisitCallSiteMain(ServiceCallSite callSite, TArgument argument)
   at Microsoft.Extensions.DependencyInjection.ServiceLookup.CallSiteRuntimeResolver.VisitCache(ServiceCallSite callSite, RuntimeResolverContext context, ServiceProviderEngineScope serviceProviderEngine, RuntimeResolverLock lockType)
   at Microsoft.Extensions.DependencyInjection.ServiceLookup.CallSiteRuntimeResolver.VisitRootCache(ServiceCallSite singletonCallSite, RuntimeResolverContext context)
   at Microsoft.Extensions.DependencyInjection.ServiceLookup.CallSiteVisitor`2.VisitCallSite(ServiceCallSite callSite, TArgument argument)
   at Microsoft.Extensions.DependencyInjection.ServiceLookup.CallSiteRuntimeResolver.Resolve(ServiceCallSite callSite, ServiceProviderEngineScope scope)
   at Microsoft.Extensions.DependencyInjection.ServiceLookup.DynamicServiceProviderEngine.<>c__DisplayClass1_0.<RealizeService>b__0(ServiceProviderEngineScope scope)
   at Microsoft.Extensions.DependencyInjection.ServiceLookup.ServiceProviderEngine.GetService(Type serviceType, ServiceProviderEngineScope serviceProviderEngineScope)
   at Microsoft.Extensions.DependencyInjection.ServiceLookup.ServiceProviderEngine.GetService(Type serviceType)
   at Microsoft.Extensions.DependencyInjection.ServiceProvider.GetService(Type serviceType)
   at Microsoft.Extensions.DependencyInjection.ServiceProviderServiceExtensions.GetRequiredService(IServiceProvider provider, Type serviceType)
   at Microsoft.Extensions.DependencyInjection.ServiceProviderServiceExtensions.GetRequiredService[T](IServiceProvider provider)
   at Microsoft.AspNetCore.Hosting.WebHost.EnsureServer()
   at Microsoft.AspNetCore.Hosting.WebHost.BuildApplication()
The thread 0x2d04 has exited with code 0 (0x0).
Exception thrown: 'System.NullReferenceException' in System.Private.CoreLib.dll
Exception thrown: 'System.NullReferenceException' in MyProjectWeb.Main.dll

The following error is present in the EventLog:

Source: IIS Express AspNetCore Module V2
Error Message: Application '/LM/W3SVC/3/ROOT' with physical root 'C:\Project_B_Source\GITHUB\bitexperts\BxWeb.Main\' failed to load clr and managed application. CLR worker thread exited prematurely

The above callstack does not contain my custom code - it is all Microsoft's framework code. I wonder how to troubleshoot this error any further?