diff --git a/.vscode/settings.json b/.vscode/settings.json
index 851f13bf..58987349 100644
--- a/.vscode/settings.json
+++ b/.vscode/settings.json
@@ -2,7 +2,8 @@
   "editor.detectIndentation": false,
   "editor.insertSpaces": true,
   "editor.tabSize": 2,
+  "omnisharp.enableEditorConfigSupport": true,
   "files.associations": {
     "*.md": "mdx"
-  },
+  }
 }
diff --git a/SpotifyAPI.Web.Auth/AuthException.cs b/SpotifyAPI.Web.Auth/AuthException.cs
index 41e1bdf3..aec059fb 100644
--- a/SpotifyAPI.Web.Auth/AuthException.cs
+++ b/SpotifyAPI.Web.Auth/AuthException.cs
@@ -3,7 +3,7 @@ namespace SpotifyAPI.Web.Auth
   [System.Serializable]
   public class AuthException : System.Exception
   {
-    public AuthException(string error, string state)
+    public AuthException(string? error, string? state)
     {
       Error = error;
       State = state;
diff --git a/SpotifyAPI.Web.Auth/EmbedIOAuthServer.cs b/SpotifyAPI.Web.Auth/EmbedIOAuthServer.cs
index 97cb7d99..42de59e7 100644
--- a/SpotifyAPI.Web.Auth/EmbedIOAuthServer.cs
+++ b/SpotifyAPI.Web.Auth/EmbedIOAuthServer.cs
@@ -35,16 +35,17 @@ namespace SpotifyAPI.Web.Auth
         .WithModule(new ActionModule("/", HttpVerbs.Post, (ctx) =>
         {
           var query = ctx.Request.QueryString;
-          if (query["error"] != null)
+          var error = query["error"];
+          if (error != null)
           {
-            throw new AuthException(query["error"], query["state"]);
+            throw new AuthException(error, query["state"]);
           }
 
           var requestType = query.Get("request_type");
           if (requestType == "token")
           {
             ImplictGrantReceived?.Invoke(this, new ImplictGrantResponse(
-              query["access_token"], query["token_type"], int.Parse(query["expires_in"])
+              query["access_token"]!, query["token_type"]!, int.Parse(query["expires_in"]!)
             )
             {
               State = query["state"]
@@ -52,7 +53,7 @@ namespace SpotifyAPI.Web.Auth
           }
           if (requestType == "code")
           {
-            AuthorizationCodeReceived?.Invoke(this, new AuthorizationCodeResponse(query["code"])
+            AuthorizationCodeReceived?.Invoke(this, new AuthorizationCodeResponse(query["code"]!)
             {
               State = query["state"]
             });
diff --git a/SpotifyAPI.Web.Auth/Models/Response/AuthorizationCodeResponse.cs b/SpotifyAPI.Web.Auth/Models/Response/AuthorizationCodeResponse.cs
index 13d43608..b83bec2a 100644
--- a/SpotifyAPI.Web.Auth/Models/Response/AuthorizationCodeResponse.cs
+++ b/SpotifyAPI.Web.Auth/Models/Response/AuthorizationCodeResponse.cs
@@ -10,6 +10,6 @@ namespace SpotifyAPI.Web.Auth
     }
 
     public string Code { get; set; } = default!;
-    public string State { get; set; } = default!;
+    public string? State { get; set; } = default!;
   }
 }
diff --git a/SpotifyAPI.Web.Auth/Models/Response/ImplicitGrantResponse.cs b/SpotifyAPI.Web.Auth/Models/Response/ImplicitGrantResponse.cs
index 2950923e..7f8e256f 100644
--- a/SpotifyAPI.Web.Auth/Models/Response/ImplicitGrantResponse.cs
+++ b/SpotifyAPI.Web.Auth/Models/Response/ImplicitGrantResponse.cs
@@ -17,7 +17,7 @@ namespace SpotifyAPI.Web.Auth
     public string AccessToken { get; set; } = default!;
     public string TokenType { get; set; } = default!;
     public int ExpiresIn { get; set; }
-    public string State { get; set; } = default!;
+    public string? State { get; set; } = default!;
 
     /// <summary>
     ///   Auto-Initalized to UTC Now
diff --git a/SpotifyAPI.Web.Auth/SpotifyAPI.Web.Auth.csproj b/SpotifyAPI.Web.Auth/SpotifyAPI.Web.Auth.csproj
index 6abdd41d..8f47dbe7 100644
--- a/SpotifyAPI.Web.Auth/SpotifyAPI.Web.Auth.csproj
+++ b/SpotifyAPI.Web.Auth/SpotifyAPI.Web.Auth.csproj
@@ -1,7 +1,7 @@
 <Project Sdk="Microsoft.NET.Sdk">
   <PropertyGroup>
-    <TargetFrameworks>netstandard2.1;netstandard2.0</TargetFrameworks>
-    <LangVersion>8.0</LangVersion>
+    <TargetFrameworks>net5.0;netstandard2.1;netstandard2.0</TargetFrameworks>
+    <LangVersion>9.0</LangVersion>
     <Nullable>enable</Nullable>
     <PackageId>SpotifyAPI.Web.Auth</PackageId>
     <Title>SpotifyAPI.Web.Auth</Title>
diff --git a/SpotifyAPI.Web.Examples/Example.ASP/Example.ASP.csproj b/SpotifyAPI.Web.Examples/Example.ASP/Example.ASP.csproj
index 823fc83b..21fde54d 100644
--- a/SpotifyAPI.Web.Examples/Example.ASP/Example.ASP.csproj
+++ b/SpotifyAPI.Web.Examples/Example.ASP/Example.ASP.csproj
@@ -1,7 +1,7 @@
 <?xml version="1.0" encoding="utf-8"?>
 <Project Sdk="Microsoft.NET.Sdk.Web">
   <PropertyGroup>
-    <TargetFramework>netcoreapp3.1</TargetFramework>
+    <TargetFramework>net5.0</TargetFramework>
     <UserSecretsId>da29eac4-4c22-4a7f-b393-379e83b60998</UserSecretsId>
   </PropertyGroup>
   <ItemGroup>
diff --git a/SpotifyAPI.Web.Examples/Example.ASPBlazor/App.razor b/SpotifyAPI.Web.Examples/Example.ASPBlazor/App.razor
index bf6c7737..38f2a1c4 100644
--- a/SpotifyAPI.Web.Examples/Example.ASPBlazor/App.razor
+++ b/SpotifyAPI.Web.Examples/Example.ASPBlazor/App.razor
@@ -1,11 +1,10 @@
-
-<Router AppAssembly="@typeof(Program).Assembly">
-    <Found Context="routeData">
-        <RouteView RouteData="@routeData" DefaultLayout="@typeof(MainLayout)" />
-    </Found>
-    <NotFound>
-        <LayoutView Layout="@typeof(MainLayout)">
-            <p>Sorry, there's nothing at this address.</p>
-        </LayoutView>
-    </NotFound>
+<Router AppAssembly="@typeof(Program).Assembly">
+  <Found Context="routeData">
+    <RouteView RouteData="@routeData" DefaultLayout="@typeof(MainLayout)" />
+  </Found>
+  <NotFound>
+    <LayoutView Layout="@typeof(MainLayout)">
+      <p>Sorry, there's nothing at this address.</p>
+    </LayoutView>
+  </NotFound>
 </Router>
diff --git a/SpotifyAPI.Web.Examples/Example.ASPBlazor/Example.ASPBlazor.csproj b/SpotifyAPI.Web.Examples/Example.ASPBlazor/Example.ASPBlazor.csproj
index f8ff38d1..4ec3d7a1 100644
--- a/SpotifyAPI.Web.Examples/Example.ASPBlazor/Example.ASPBlazor.csproj
+++ b/SpotifyAPI.Web.Examples/Example.ASPBlazor/Example.ASPBlazor.csproj
@@ -1,7 +1,7 @@
 <Project Sdk="Microsoft.NET.Sdk.Web">
 
   <PropertyGroup>
-    <TargetFramework>netcoreapp3.1</TargetFramework>
+    <TargetFramework>net5.0</TargetFramework>
   </PropertyGroup>
 
   <ItemGroup>
diff --git a/SpotifyAPI.Web.Examples/Example.BlazorWASM/App.razor b/SpotifyAPI.Web.Examples/Example.BlazorWASM/App.razor
index 6f67a6ea..2d39d607 100644
--- a/SpotifyAPI.Web.Examples/Example.BlazorWASM/App.razor
+++ b/SpotifyAPI.Web.Examples/Example.BlazorWASM/App.razor
@@ -1,10 +1,10 @@
 <Router AppAssembly="@typeof(Program).Assembly">
-    <Found Context="routeData">
-        <RouteView RouteData="@routeData" DefaultLayout="@typeof(MainLayout)" />
-    </Found>
-    <NotFound>
-        <LayoutView Layout="@typeof(MainLayout)">
-            <p>Sorry, there's nothing at this address.</p>
-        </LayoutView>
-    </NotFound>
+  <Found Context="routeData">
+    <RouteView RouteData="@routeData" DefaultLayout="@typeof(MainLayout)" />
+  </Found>
+  <NotFound>
+    <LayoutView Layout="@typeof(MainLayout)">
+      <p>Sorry, there's nothing at this address.</p>
+    </LayoutView>
+  </NotFound>
 </Router>
diff --git a/SpotifyAPI.Web.Examples/Example.BlazorWASM/Example.BlazorWASM.csproj b/SpotifyAPI.Web.Examples/Example.BlazorWASM/Example.BlazorWASM.csproj
index adb230ee..4999ca13 100644
--- a/SpotifyAPI.Web.Examples/Example.BlazorWASM/Example.BlazorWASM.csproj
+++ b/SpotifyAPI.Web.Examples/Example.BlazorWASM/Example.BlazorWASM.csproj
@@ -1,7 +1,7 @@
 <Project Sdk="Microsoft.NET.Sdk.Web">
 
   <PropertyGroup>
-    <TargetFramework>netstandard2.1</TargetFramework>
+    <TargetFramework>net5.0</TargetFramework>
     <RazorLangVersion>3.0</RazorLangVersion>
   </PropertyGroup>
 
diff --git a/SpotifyAPI.Web.Examples/Example.CLI.CustomHTML/Example.CLI.CustomHTML.csproj b/SpotifyAPI.Web.Examples/Example.CLI.CustomHTML/Example.CLI.CustomHTML.csproj
index 53f289a9..12043086 100644
--- a/SpotifyAPI.Web.Examples/Example.CLI.CustomHTML/Example.CLI.CustomHTML.csproj
+++ b/SpotifyAPI.Web.Examples/Example.CLI.CustomHTML/Example.CLI.CustomHTML.csproj
@@ -6,8 +6,8 @@
   </ItemGroup>
 
   <PropertyGroup>
+    <TargetFramework>net5.0</TargetFramework>
     <OutputType>Exe</OutputType>
-    <TargetFramework>netcoreapp3.1</TargetFramework>
   </PropertyGroup>
 
   <ItemGroup>
diff --git a/SpotifyAPI.Web.Examples/Example.TokenSwap/Client/Client.csproj b/SpotifyAPI.Web.Examples/Example.TokenSwap/Client/Client.csproj
index 49665eb7..e57fedf9 100644
--- a/SpotifyAPI.Web.Examples/Example.TokenSwap/Client/Client.csproj
+++ b/SpotifyAPI.Web.Examples/Example.TokenSwap/Client/Client.csproj
@@ -6,8 +6,8 @@
   </ItemGroup>
 
   <PropertyGroup>
+    <TargetFramework>net5.0</TargetFramework>
     <OutputType>Exe</OutputType>
-    <TargetFramework>netcoreapp3.1</TargetFramework>
   </PropertyGroup>
 
 </Project>
diff --git a/SpotifyAPI.Web.Tests/SpotifyAPI.Web.Tests.csproj b/SpotifyAPI.Web.Tests/SpotifyAPI.Web.Tests.csproj
index b720ec21..fb1f3989 100644
--- a/SpotifyAPI.Web.Tests/SpotifyAPI.Web.Tests.csproj
+++ b/SpotifyAPI.Web.Tests/SpotifyAPI.Web.Tests.csproj
@@ -1,7 +1,7 @@
 <Project Sdk="Microsoft.NET.Sdk">
 
   <PropertyGroup>
-    <TargetFrameworks>netcoreapp3.1;netcoreapp2.2</TargetFrameworks>
+    <TargetFrameworks>net5.0;netcoreapp3.1;netcoreapp2.2</TargetFrameworks>
     <IsPackable>false</IsPackable>
   </PropertyGroup>
 
diff --git a/SpotifyAPI.Web/Clients/OAuthClient.cs b/SpotifyAPI.Web/Clients/OAuthClient.cs
index dd2b77c4..06bfb7c8 100644
--- a/SpotifyAPI.Web/Clients/OAuthClient.cs
+++ b/SpotifyAPI.Web/Clients/OAuthClient.cs
@@ -112,13 +112,13 @@ namespace SpotifyAPI.Web
       Ensure.ArgumentNotNull(request, nameof(request));
       Ensure.ArgumentNotNull(apiConnector, nameof(apiConnector));
 
-      var form = new List<KeyValuePair<string, string>>
+      var form = new List<KeyValuePair<string?, string?>>
       {
-        new KeyValuePair<string, string>("client_id", request.ClientId),
-        new KeyValuePair<string, string>("grant_type", "authorization_code"),
-        new KeyValuePair<string, string>("code", request.Code),
-        new KeyValuePair<string, string>("redirect_uri", request.RedirectUri.ToString()),
-        new KeyValuePair<string, string>("code_verifier", request.CodeVerifier),
+        new KeyValuePair<string?, string?>("client_id", request.ClientId),
+        new KeyValuePair<string?, string?>("grant_type", "authorization_code"),
+        new KeyValuePair<string?, string?>("code", request.Code),
+        new KeyValuePair<string?, string?>("redirect_uri", request.RedirectUri.ToString()),
+        new KeyValuePair<string?, string?>("code_verifier", request.CodeVerifier),
       };
 
       return SendOAuthRequest<PKCETokenResponse>(apiConnector, form, null, null);
@@ -129,11 +129,11 @@ namespace SpotifyAPI.Web
       Ensure.ArgumentNotNull(request, nameof(request));
       Ensure.ArgumentNotNull(apiConnector, nameof(apiConnector));
 
-      var form = new List<KeyValuePair<string, string>>
+      var form = new List<KeyValuePair<string?, string?>>
       {
-        new KeyValuePair<string, string>("client_id", request.ClientId),
-        new KeyValuePair<string, string>("grant_type", "refresh_token"),
-        new KeyValuePair<string, string>("refresh_token", request.RefreshToken),
+        new KeyValuePair<string?, string?>("client_id", request.ClientId),
+        new KeyValuePair<string?, string?>("grant_type", "refresh_token"),
+        new KeyValuePair<string?, string?>("refresh_token", request.RefreshToken),
       };
 
       return SendOAuthRequest<PKCETokenResponse>(apiConnector, form, null, null);
@@ -146,9 +146,9 @@ namespace SpotifyAPI.Web
       Ensure.ArgumentNotNull(request, nameof(request));
       Ensure.ArgumentNotNull(apiConnector, nameof(apiConnector));
 
-      var form = new List<KeyValuePair<string, string>>
+      var form = new List<KeyValuePair<string?, string?>>
       {
-        new KeyValuePair<string, string>("refresh_token", request.RefreshToken)
+        new KeyValuePair<string?, string?>("refresh_token", request.RefreshToken)
       };
 #pragma warning disable CA2000
       return apiConnector.Post<AuthorizationCodeRefreshResponse>(
@@ -164,9 +164,9 @@ namespace SpotifyAPI.Web
       Ensure.ArgumentNotNull(request, nameof(request));
       Ensure.ArgumentNotNull(apiConnector, nameof(apiConnector));
 
-      var form = new List<KeyValuePair<string, string>>
+      var form = new List<KeyValuePair<string?, string?>>
       {
-        new KeyValuePair<string, string>("code", request.Code)
+        new KeyValuePair<string?, string?>("code", request.Code)
       };
 
 #pragma warning disable CA2000
@@ -183,9 +183,9 @@ namespace SpotifyAPI.Web
       Ensure.ArgumentNotNull(request, nameof(request));
       Ensure.ArgumentNotNull(apiConnector, nameof(apiConnector));
 
-      var form = new List<KeyValuePair<string, string>>
+      var form = new List<KeyValuePair<string?, string?>>
       {
-        new KeyValuePair<string, string>("grant_type", "client_credentials")
+        new KeyValuePair<string?, string?>("grant_type", "client_credentials")
       };
 
       return SendOAuthRequest<ClientCredentialsTokenResponse>(apiConnector, form, request.ClientId, request.ClientSecret);
@@ -198,10 +198,10 @@ namespace SpotifyAPI.Web
       Ensure.ArgumentNotNull(request, nameof(request));
       Ensure.ArgumentNotNull(apiConnector, nameof(apiConnector));
 
-      var form = new List<KeyValuePair<string, string>>
+      var form = new List<KeyValuePair<string?, string?>>
       {
-        new KeyValuePair<string, string>("grant_type", "refresh_token"),
-        new KeyValuePair<string, string>("refresh_token", request.RefreshToken)
+        new KeyValuePair<string?, string?>("grant_type", "refresh_token"),
+        new KeyValuePair<string?, string?>("refresh_token", request.RefreshToken)
       };
 
       return SendOAuthRequest<AuthorizationCodeRefreshResponse>(apiConnector, form, request.ClientId, request.ClientSecret);
@@ -214,11 +214,11 @@ namespace SpotifyAPI.Web
       Ensure.ArgumentNotNull(request, nameof(request));
       Ensure.ArgumentNotNull(apiConnector, nameof(apiConnector));
 
-      var form = new List<KeyValuePair<string, string>>
+      var form = new List<KeyValuePair<string?, string?>>
       {
-        new KeyValuePair<string, string>("grant_type", "authorization_code"),
-        new KeyValuePair<string, string>("code", request.Code),
-        new KeyValuePair<string, string>("redirect_uri", request.RedirectUri.ToString())
+        new KeyValuePair<string?, string?>("grant_type", "authorization_code"),
+        new KeyValuePair<string?, string?>("code", request.Code),
+        new KeyValuePair<string?, string?>("redirect_uri", request.RedirectUri.ToString())
       };
 
       return SendOAuthRequest<AuthorizationCodeTokenResponse>(apiConnector, form, request.ClientId, request.ClientSecret);
@@ -226,7 +226,7 @@ namespace SpotifyAPI.Web
 
     private static Task<T> SendOAuthRequest<T>(
       IAPIConnector apiConnector,
-      List<KeyValuePair<string, string>> form,
+      List<KeyValuePair<string?, string?>> form,
       string? clientId,
       string? clientSecret)
     {
diff --git a/SpotifyAPI.Web/Clients/SimplePaginator.cs b/SpotifyAPI.Web/Clients/SimplePaginator.cs
index 92f35dac..b6e2c2e1 100644
--- a/SpotifyAPI.Web/Clients/SimplePaginator.cs
+++ b/SpotifyAPI.Web/Clients/SimplePaginator.cs
@@ -25,11 +25,17 @@ namespace SpotifyAPI.Web
 
       var page = firstPage;
       var results = new List<T>();
-      results.AddRange(firstPage.Items);
+      if (page.Items != null)
+      {
+        results.AddRange(page.Items);
+      }
       while (page.Next != null && await ShouldContinue(results, page).ConfigureAwait(false))
       {
         page = await connector.Get<Paging<T>>(new Uri(page.Next, UriKind.Absolute)).ConfigureAwait(false);
-        results.AddRange(page.Items);
+        if (page.Items != null)
+        {
+          results.AddRange(page.Items);
+        }
       }
 
       return results;
@@ -45,12 +51,18 @@ namespace SpotifyAPI.Web
 
       var page = firstPage;
       var results = new List<T>();
-      results.AddRange(firstPage.Items);
+      if (page.Items != null)
+      {
+        results.AddRange(page.Items);
+      }
       while (page.Next != null && await ShouldContinue(results, page).ConfigureAwait(false))
       {
         var next = await connector.Get<TNext>(new Uri(page.Next, UriKind.Absolute)).ConfigureAwait(false);
         page = mapper(next);
-        results.AddRange(page.Items);
+        if (page.Items != null)
+        {
+          results.AddRange(page.Items);
+        }
       }
 
       return results;
diff --git a/SpotifyAPI.Web/Clients/SpotifyClient.cs b/SpotifyAPI.Web/Clients/SpotifyClient.cs
index 8439ce28..31bcad71 100644
--- a/SpotifyAPI.Web/Clients/SpotifyClient.cs
+++ b/SpotifyAPI.Web/Clients/SpotifyClient.cs
@@ -191,7 +191,7 @@ namespace SpotifyAPI.Web
 
       var firstPage = await getFirstPage().ConfigureAwait(false);
       await foreach (var item in (paginator ?? DefaultPaginator)
-        .Paginate(firstPage, mapper, _apiConnector)
+        .Paginate(firstPage, mapper, _apiConnector, cancellationToken)
         .WithCancellation(cancellationToken)
       )
       {
@@ -223,7 +223,7 @@ namespace SpotifyAPI.Web
 
       var firstPage = await firstPageTask.ConfigureAwait(false);
       await foreach (var item in (paginator ?? DefaultPaginator)
-        .Paginate(firstPage, mapper, _apiConnector)
+        .Paginate(firstPage, mapper, _apiConnector, cancellationToken)
         .WithCancellation(cancellationToken)
       )
       {
diff --git a/SpotifyAPI.Web/Exceptions/APITooManyRequestsException.cs b/SpotifyAPI.Web/Exceptions/APITooManyRequestsException.cs
index acfdac69..2ea206dd 100644
--- a/SpotifyAPI.Web/Exceptions/APITooManyRequestsException.cs
+++ b/SpotifyAPI.Web/Exceptions/APITooManyRequestsException.cs
@@ -14,7 +14,7 @@ namespace SpotifyAPI.Web
     {
       Ensure.ArgumentNotNull(response, nameof(response));
 
-      if (response.Headers.TryGetValue("Retry-After", out string retryAfter))
+      if (response.Headers.TryGetValue("Retry-After", out string? retryAfter))
       {
         RetryAfter = TimeSpan.FromSeconds(int.Parse(retryAfter, CultureInfo.InvariantCulture));
       }
diff --git a/SpotifyAPI.Web/Http/APIConnector.cs b/SpotifyAPI.Web/Http/APIConnector.cs
index e75069e8..ecc24862 100644
--- a/SpotifyAPI.Web/Http/APIConnector.cs
+++ b/SpotifyAPI.Web/Http/APIConnector.cs
@@ -254,7 +254,7 @@ namespace SpotifyAPI.Web.Http
     {
       var request = CreateRequest(uri, method, parameters, body, headers);
       IAPIResponse<T> apiResponse = await DoSerializedRequest<T>(request).ConfigureAwait(false);
-      return apiResponse.Body;
+      return apiResponse.Body!;
     }
 
     public async Task<IResponse> SendAPIRequestDetailed(
diff --git a/SpotifyAPI.Web/Http/APIResponse.cs b/SpotifyAPI.Web/Http/APIResponse.cs
index 48e0ba47..6700a17e 100644
--- a/SpotifyAPI.Web/Http/APIResponse.cs
+++ b/SpotifyAPI.Web/Http/APIResponse.cs
@@ -2,7 +2,7 @@ namespace SpotifyAPI.Web.Http
 {
   public class APIResponse<T> : IAPIResponse<T>
   {
-    public APIResponse(IResponse response, T body = default)
+    public APIResponse(IResponse response, T? body = default)
     {
       Ensure.ArgumentNotNull(response, nameof(response));
 
@@ -10,7 +10,7 @@ namespace SpotifyAPI.Web.Http
       Response = response;
     }
 
-    public T Body { get; set; }
+    public T? Body { get; set; }
 
     public IResponse Response { get; set; }
   }
diff --git a/SpotifyAPI.Web/Http/Interfaces/IAPIResponse.cs b/SpotifyAPI.Web/Http/Interfaces/IAPIResponse.cs
index 2de5db76..aa2513be 100644
--- a/SpotifyAPI.Web/Http/Interfaces/IAPIResponse.cs
+++ b/SpotifyAPI.Web/Http/Interfaces/IAPIResponse.cs
@@ -2,7 +2,7 @@ namespace SpotifyAPI.Web.Http
 {
   public interface IAPIResponse<out T>
   {
-    T Body { get; }
+    T? Body { get; }
 
     IResponse Response { get; }
   }
diff --git a/SpotifyAPI.Web/Http/SimpleConsoleHTTPLogger.cs b/SpotifyAPI.Web/Http/SimpleConsoleHTTPLogger.cs
index d202f70b..9fb3e0ae 100644
--- a/SpotifyAPI.Web/Http/SimpleConsoleHTTPLogger.cs
+++ b/SpotifyAPI.Web/Http/SimpleConsoleHTTPLogger.cs
@@ -15,7 +15,9 @@ namespace SpotifyAPI.Web.Http
       string? parameters = null;
       if (request.Parameters != null)
       {
-        parameters = string.Join(",", request.Parameters?.Select(kv => kv.Key + "=" + kv.Value).ToArray());
+        parameters = string.Join(",",
+          request.Parameters?.Select(kv => kv.Key + "=" + kv.Value)?.ToArray() ?? Array.Empty<string>()
+        );
       }
 
       Console.WriteLine(OnRequestFormat, request.Method, request.Endpoint, parameters, request.Body);
@@ -28,7 +30,7 @@ namespace SpotifyAPI.Web.Http
 #if NETSTANDARD2_0
       string? body = response.Body?.ToString().Replace("\n", "");
 #else
-      string? body = response.Body?.ToString().Replace("\n", "", StringComparison.InvariantCulture);
+      string? body = response.Body?.ToString()?.Replace("\n", "", StringComparison.InvariantCulture);
 #endif
 
       body = body?.Substring(0, Math.Min(50, body?.Length ?? 0));
diff --git a/SpotifyAPI.Web/Models/Request/RequestParams.cs b/SpotifyAPI.Web/Models/Request/RequestParams.cs
index d5cc3319..97a05bd7 100644
--- a/SpotifyAPI.Web/Models/Request/RequestParams.cs
+++ b/SpotifyAPI.Web/Models/Request/RequestParams.cs
@@ -37,9 +37,12 @@ namespace SpotifyAPI.Web
         _bodyParamsCache[type] = new List<(PropertyInfo, BodyParamAttribute)>();
         foreach (var prop in bodyProps)
         {
-          var attribute = (BodyParamAttribute)prop.GetCustomAttribute(typeof(BodyParamAttribute));
-          _bodyParamsCache[type].Add((prop, attribute));
-          AddBodyParam(body, prop, attribute);
+          var attribute = prop.GetCustomAttribute<BodyParamAttribute>();
+          if (attribute != null)
+          {
+            _bodyParamsCache[type].Add((prop, attribute));
+            AddBodyParam(body, prop, attribute);
+          }
         }
       }
 
@@ -48,7 +51,7 @@ namespace SpotifyAPI.Web
 
     private void AddBodyParam(JObject body, PropertyInfo prop, BodyParamAttribute attribute)
     {
-      object value = prop.GetValue(this);
+      object? value = prop.GetValue(this);
       if (value != null)
       {
         body[attribute.Key ?? prop.Name] = JToken.FromObject(value);
@@ -81,9 +84,12 @@ namespace SpotifyAPI.Web
         _queryParamsCache[type] = new List<(PropertyInfo, QueryParamAttribute)>();
         foreach (var prop in queryProps)
         {
-          var attribute = (QueryParamAttribute)prop.GetCustomAttribute(typeof(QueryParamAttribute));
-          _queryParamsCache[type].Add((prop, attribute));
-          AddQueryParam(queryParams, prop, attribute);
+          var attribute = prop.GetCustomAttribute<QueryParamAttribute>();
+          if (attribute != null)
+          {
+            _queryParamsCache[type].Add((prop, attribute));
+            AddQueryParam(queryParams, prop, attribute);
+          }
         }
       }
 
@@ -94,7 +100,7 @@ namespace SpotifyAPI.Web
 
     private void AddQueryParam(Dictionary<string, string> queryParams, PropertyInfo prop, QueryParamAttribute attribute)
     {
-      object value = prop.GetValue(this);
+      object? value = prop.GetValue(this);
       if (value != null)
       {
         if (value is IList<string> list)
@@ -140,7 +146,7 @@ namespace SpotifyAPI.Web
         }
         else
         {
-          queryParams.Add(attribute.Key ?? prop.Name, value.ToString());
+          queryParams.Add(attribute.Key ?? prop.Name, value.ToString() ?? throw new Exception("ToString was null on a value"));
         }
       }
     }
diff --git a/SpotifyAPI.Web/RetryHandlers/SimpleRetryHandler.cs b/SpotifyAPI.Web/RetryHandlers/SimpleRetryHandler.cs
index 63ff0ef4..9bb5f348 100644
--- a/SpotifyAPI.Web/RetryHandlers/SimpleRetryHandler.cs
+++ b/SpotifyAPI.Web/RetryHandlers/SimpleRetryHandler.cs
@@ -70,6 +70,7 @@ namespace SpotifyAPI.Web
     public Task<IResponse> HandleRetry(IRequest request, IResponse response, IRetryHandler.RetryFunc retry)
     {
       Ensure.ArgumentNotNull(response, nameof(response));
+      Ensure.ArgumentNotNull(retry, nameof(retry));
 
       return HandleRetryInternally(request, response, retry, RetryTimes);
     }
diff --git a/SpotifyAPI.Web/SpotifyAPI.Web.csproj b/SpotifyAPI.Web/SpotifyAPI.Web.csproj
index 7dd57e95..9d1cd506 100644
--- a/SpotifyAPI.Web/SpotifyAPI.Web.csproj
+++ b/SpotifyAPI.Web/SpotifyAPI.Web.csproj
@@ -1,8 +1,8 @@
 <Project Sdk="Microsoft.NET.Sdk">
 
   <PropertyGroup>
-    <TargetFrameworks>netstandard2.1;netstandard2.0</TargetFrameworks>
-    <LangVersion>8.0</LangVersion>
+    <TargetFrameworks>net5.0;netstandard2.1;netstandard2.0</TargetFrameworks>
+    <LangVersion>9.0</LangVersion>
     <Nullable>enable</Nullable>
     <PackageId>SpotifyAPI.Web</PackageId>
     <Title>SpotifyAPI.Web</Title>
diff --git a/SpotifyAPI.Web/Util/StringAttribute.cs b/SpotifyAPI.Web/Util/StringAttribute.cs
index d0d54873..d54e39df 100644
--- a/SpotifyAPI.Web/Util/StringAttribute.cs
+++ b/SpotifyAPI.Web/Util/StringAttribute.cs
@@ -15,11 +15,10 @@ namespace SpotifyAPI.Web
 
     public string Value { get; set; }
 
-#if NETSTANDARD2_1
-    public static bool GetValue(Type enumType, Enum enumValue, [NotNullWhen(true)] out string? result)
-#endif
 #if NETSTANDARD2_0
     public static bool GetValue(Type enumType, Enum enumValue, out string? result)
+#else
+    public static bool GetValue(Type enumType, Enum enumValue, [NotNullWhen(true)] out string? result)
 #endif
     {
       Ensure.ArgumentNotNull(enumType, nameof(enumType));
diff --git a/SpotifyAPI.Web/Util/URIExtension.cs b/SpotifyAPI.Web/Util/URIExtension.cs
index c5d3a478..eae2e87d 100644
--- a/SpotifyAPI.Web/Util/URIExtension.cs
+++ b/SpotifyAPI.Web/Util/URIExtension.cs
@@ -19,9 +19,9 @@ namespace SpotifyAPI.Web
 
       var newParameters = new Dictionary<string, string>();
       NameValueCollection existingParameters = HttpUtility.ParseQueryString(uri.Query);
-      foreach (string key in existingParameters.AllKeys)
+      foreach (string key in existingParameters)
       {
-        newParameters.Add(key, existingParameters[key]);
+        newParameters.Add(key, existingParameters[key]!);
       }
       foreach (KeyValuePair<string, string> parameter in parameters)
       {
diff --git a/SpotifyAPI.Web/Util/URIParameterFormatProvider.cs b/SpotifyAPI.Web/Util/URIParameterFormatProvider.cs
index 6fbcd81a..3fb91a1f 100644
--- a/SpotifyAPI.Web/Util/URIParameterFormatProvider.cs
+++ b/SpotifyAPI.Web/Util/URIParameterFormatProvider.cs
@@ -11,16 +11,16 @@ namespace SpotifyAPI.Web
       _formatter = new URIParameterFormatter();
     }
 
-    public object? GetFormat(Type formatType)
+    public object? GetFormat(Type? formatType)
     {
       return formatType == typeof(ICustomFormatter) ? _formatter : null;
     }
 
     private class URIParameterFormatter : ICustomFormatter
     {
-      public string Format(string format, object arg, IFormatProvider formatProvider)
+      public string Format(string? format, object? arg, IFormatProvider? formatProvider)
       {
-        return HttpUtility.UrlEncode(arg.ToString());
+        return HttpUtility.UrlEncode(arg?.ToString()) ?? string.Empty;
       }
     }
   }