title: Cannot implicitly convert type 'Microsoft.IdentityModel.Tokens.SymmetricSecurityKey' to 'Microsoft.IdentityModel.Tokens.IssuerSigningKeyResolver'
body: <p>I am new to working with C#. I am working on a course using it for the first time. I am following the Neil Cummings course on building an app with asp.netcore and angular. I get a CS0029, I understand that I am returning the wrong type, what I do not understand is how to fix/remove the error?
  my code:
  the error happens by 'IssuerSigningKey = new SymmetricKey...'</p>
  <pre><code>using System.Text;
  using Microsoft.AspNetCore.Authentication.JwtBearer;
  using Microsoft.IdentityModel.Tokens;
  
  namespace API.Extensions.DependencyInjection
  {
      public static class IdentityServiceExtensions
      {
          public static IServiceCollection AddIdentityServices(this IServiceCollection services, IConfiguration config)
          {
              services.AddAuthentication(JwtBearerDefaults.AuthenticationScheme)
                  .AddJwtBearer(options =&gt;
          {
              options.TokenValidationParameters = new TokenValidationParameters
              {
                  ValidateIssuerSigningKey = true,
                  IssuerSigningKeyResolver = new SymmetricSecurityKey(Encoding.UTF8.GetBytes(config[&quot;TokenKey&quot;])), //error here
                  ValidateIssuer = false,
                  ValidateAudience = false,
              };
          });
  
          return services;
          }
  </code></pre>
  <p>It is also my first time using Stackoverflow, so I hope I have posted my question correctly?</p>
  <p>Many thanks for the assistance in advance!</p>