I’m failing to connect to PostgreSQL using Npgsql in my local environment I have checked each and every thing looks fine and I’m able to connect using my pgAmin and also I have managed to update tables after creating migrations I don’t know where I’m doing it wrong where I try to open the connection so as I can insert data into the table I have created below is my implementation.

appsettings.json

{
  "ConnectionStrings": {
    "DefaultConnection": "Host=localhost;Port=5432;Database=customerdb;Username=postgres;Password=admin123;"
  },
  "Logging": {
    "LogLevel": {
      "Default": "Information",
      "Microsoft.AspNetCore": "Warning"
    }
  },
  "AllowedHosts": "*"
}

Controller method to insert data

 private readonly string _connectionString;

  public DataLoader(string connectionString)
  {
  _connectionString = connectionString;
  }

    public async Task LoadToDatabase(IEnumerable<Customer> data)
     {
    
         try
         {
             await using var connection = new NpgsqlConnection(_connectionString);
             await connection.OpenAsync();
    
             foreach (var customerDetails in data)
             {
             await connection.ExecuteAsync("INSERT INTO Customer (CustomerCode, CustomerNames,OrderId, Location) VALUES (@CustomerCode, @CustomerNames, @OrderId, @Location)", customerDetails);
             }
    
             await connection.CloseAsync();
         }
         catch (NpgsqlException ex)
         {
             // Log error (log to a file, console, etc.)
             Console.WriteLine($"Error opening PostgreSQL connection: {ex.Message}");
         }
         catch (Exception ex)
         {
             // Log error (log to a file, console, etc.)
             Console.WriteLine($"An error occurred: {ex.Message}");
         }
     }

Program .CS class

// Add services to the container.
builder.Services.AddControllers();

// Adding configuration
builder.Configuration.AddJsonFile(“appsettings.json”, optional: false, reloadOnChange: true);

// Getting the configuration
var configuration = builder.Configuration;

// Retrieving connection string from configuration
var postgreconnection = configuration.GetSection("ConnectionStrings:DefaultConnection").Value;

// Configuring PostgreSQL Database connection
builder.Services.AddDbContext<ApplicationDbContext>(options =>options.UseNpgsql(postgreconnection));

// Learn more about configuring Swagger/OpenAPI at https://aka.ms/aspnetcore/swashbuckle
builder.Services.AddEndpointsApiExplorer();
builder.Services.AddSwaggerGen();

builder.Services.AddSingleton(new DataExtractor());
builder.Services.AddSingleton(new DataTransformer());
builder.Services.AddSingleton(new DataLoader(postgreconnection));

No firewall is blocking, any suggestions will be much appreciated.