I am trying to reverse create the C# code from an existing database.

If I manually enter my connection string and type the command:

Scaffold-DbContext 'Data Source=MyServer;Initial Catalog=MyCatalog;Integrated Security=True;Connect Timeout=30;Encrypt=False;Trust Server Certificate=False;Application Intent=ReadWrite;Multi Subnet Failover=False'    
         Microsoft.EntityFrameworkCore.SqlServer 
         -Tables DeviceParameterWithDevice -Context DPWDContext  
         -OutputDir Models -Force

This works OK, and I get all the correct code produced.

I add the same connection string into the appsettings.json file (as well as the appsettings.Development.json file - just in case)

{
  "ConnectionStrings": {
    "EnviroWatchDB": "Data Source=MyServer;Initial Catalog=MyCatalog;Integrated Security=True;Connect Timeout=30;Encrypt=False;Trust Server Certificate=False;Application Intent=ReadWrite;Multi Subnet Failover=False"
  },
  "Logging": {
    "LogLevel": {
      "Default": "Information",
      "Microsoft.AspNetCore": "Warning"
    }
  },
  "AllowedHosts": "*"
}

If I run

Scaffold-DbContext -connection name=EnviroWatchDB     
         Microsoft.EntityFrameworkCore.SqlServer 
         -Tables DeviceParameterWithDevice -Context DPWDContext  
         -OutputDir Models

I get the following errors

Unhandled exception. Unhandled exception. Unhandled exception. System.UriFormatException: Invalid URI: The hostname could not be parsed.

at System.Uri.CreateThis(String uri, Boolean dontEscape, UriKind uriKind, UriCreationOptions& creationOptions)
at System.Uri..ctor(String uriString, UriKind uriKind)
at System.Net.Http.HttpClient.CreateUri(String uri)
at System.Net.Http.HttpClient.GetAsync(String requestUri)
at Program.<>c__DisplayClass0_2.<<$>b__1>d.MoveNext() in Z:\MyDir\Program.cs:line 111
--- End of stack trace from previous location ---
at System.Threading.Tasks.Task.<>c.b__128_1(Object state)
at System.Threading.QueueUserWorkItemCallback.Execute()
at System.Threading.ThreadPoolWorkQueue.Dispatch()
at System.Threading.PortableThreadPool.WorkerThread.WorkerThreadStart() System.UriFormatException: Invalid URI: The hostname could not be parsed.
at System.Uri.CreateThis(String uri, Boolean dontEscape, UriKind uriKind, UriCreationOptions& creationOptions)
at System.Uri..ctor(String uriString, UriKind uriKind)
at System.Net.Http.HttpClient.CreateUri(String uri)
at System.Net.Http.HttpClient.GetAsync(String requestUri)
at Program.<>c__DisplayClass0_2.<<$>b__1>d.MoveNext() in Z:\MyDirProgram.cs:line 111
--- End of stack trace from previous location ---
at System.Threading.Tasks.Task.<>c.b__128_1(Object state)
at System.Threading.QueueUserWorkItemCallback.Execute()
at System.Threading.ThreadPoolWorkQueue.Dispatch()
at System.Threading.PortableThreadPool.WorkerThread.WorkerThreadStart() System.UriFormatException: Invalid URI: The hostname could not be parsed.

I have tried adding this to the program.cs file

var connectionString = builder.Configuration.GetConnectionString("EnviroWatchDB");
builder.Services.AddDbContext<DbContext>(x => x.UseSqlServer(connectionString));

but no effect.

Any ideas what is happening?

Thanks