diff --git a/dotnet/src/webdriver/CommandInfo.cs b/dotnet/src/webdriver/CommandInfo.cs
index 0e679e221dcc7..a1bde2f141a20 100644
--- a/dotnet/src/webdriver/CommandInfo.cs
+++ b/dotnet/src/webdriver/CommandInfo.cs
@@ -19,6 +19,8 @@
 
 using System;
 
+#nullable enable
+
 namespace OpenQA.Selenium
 {
     /// <summary>
@@ -45,7 +47,7 @@ public override int GetHashCode()
         /// </summary>
         /// <param name="obj">The <see cref="CommandInfo"/> to compare to this instance.</param>
         /// <returns><see langword="true"/> if <paramref name="obj"/> is a <see cref="CommandInfo"/> and its value is the same as this instance; otherwise, <see langword="false"/>. If <paramref name="obj"/> is <see langword="null"/>, the method returns <see langword="false"/>.</returns>
-        public override bool Equals(object obj)
+        public override bool Equals(object? obj)
         {
             return this.Equals(obj as CommandInfo);
         }
@@ -55,7 +57,7 @@ public override bool Equals(object obj)
         /// </summary>
         /// <param name="other">The <see cref="CommandInfo"/> to compare to this instance.</param>
         /// <returns><see langword="true"/> if the value of the <paramref name="other"/> parameter is the same as this instance; otherwise, <see langword="false"/>. If <paramref name="other"/> is <see langword="null"/>, the method returns <see langword="false"/>.</returns>
-        public bool Equals(CommandInfo other)
+        public bool Equals(CommandInfo? other)
         {
             if (other is null)
             {
@@ -63,7 +65,7 @@ public bool Equals(CommandInfo other)
             }
 
             // Optimization for a common success case.
-            if (Object.ReferenceEquals(this, other))
+            if (object.ReferenceEquals(this, other))
             {
                 return true;
             }
@@ -86,7 +88,7 @@ public bool Equals(CommandInfo other)
         /// <param name="left">The first <see cref="CommandInfo"/> object to compare.</param>
         /// <param name="right">The second <see cref="CommandInfo"/> object to compare.</param>
         /// <returns><see langword="true"/> if the value of <paramref name="left"/> is the same as the value of <paramref name="right"/>; otherwise, <see langword="false"/>.</returns>
-        public static bool operator ==(CommandInfo left, CommandInfo right)
+        public static bool operator ==(CommandInfo? left, CommandInfo? right)
         {
             if (left is null)
             {
@@ -107,7 +109,7 @@ public bool Equals(CommandInfo other)
         /// <param name="left">The first <see cref="CommandInfo"/> object to compare.</param>
         /// <param name="right">The second <see cref="CommandInfo"/> object to compare.</param>
         /// <returns><see langword="true"/> if the value of <paramref name="left"/> is different from the value of <paramref name="right"/>; otherwise, <see langword="false"/>.</returns>
-        public static bool operator !=(CommandInfo left, CommandInfo right)
+        public static bool operator !=(CommandInfo? left, CommandInfo? right)
         {
             return !(left == right);
         }
diff --git a/dotnet/src/webdriver/HttpCommandInfo.cs b/dotnet/src/webdriver/HttpCommandInfo.cs
index 0841ffcde7524..36965d875cd5b 100644
--- a/dotnet/src/webdriver/HttpCommandInfo.cs
+++ b/dotnet/src/webdriver/HttpCommandInfo.cs
@@ -20,6 +20,8 @@
 using System;
 using System.Globalization;
 
+#nullable enable
+
 namespace OpenQA.Selenium
 {
     /// <summary>
@@ -44,9 +46,6 @@ public class HttpCommandInfo : CommandInfo
 
         private const string SessionIdPropertyName = "sessionId";
 
-        private string resourcePath;
-        private string method;
-
         /// <summary>
         /// Initializes a new instance of the <see cref="HttpCommandInfo"/> class
         /// </summary>
@@ -54,32 +53,26 @@ public class HttpCommandInfo : CommandInfo
         /// <param name="resourcePath">Relative URL path to the resource used to execute the command</param>
         public HttpCommandInfo(string method, string resourcePath)
         {
-            this.resourcePath = resourcePath;
-            this.method = method;
+            this.ResourcePath = resourcePath;
+            this.Method = method;
         }
 
         /// <summary>
         /// Gets the URL representing the path to the resource.
         /// </summary>
-        public string ResourcePath
-        {
-            get { return this.resourcePath; }
-        }
+        public string ResourcePath { get; }
 
         /// <summary>
         /// Gets the HTTP method associated with the command.
         /// </summary>
-        public string Method
-        {
-            get { return this.method; }
-        }
+        public string Method { get; }
 
         /// <summary>
         /// Gets the unique identifier for this command within the scope of its protocol definition
         /// </summary>
         public override string CommandIdentifier
         {
-            get { return string.Format(CultureInfo.InvariantCulture, "{0} {1}", this.method, this.resourcePath); }
+            get { return string.Format(CultureInfo.InvariantCulture, "{0} {1}", this.Method, this.ResourcePath); }
         }
 
         /// <summary>
@@ -93,7 +86,7 @@ public override string CommandIdentifier
         /// substituted for the tokens in the template.</returns>
         public Uri CreateCommandUri(Uri baseUri, Command commandToExecute)
         {
-            string[] urlParts = this.resourcePath.Split(new string[] { "/" }, StringSplitOptions.RemoveEmptyEntries);
+            string[] urlParts = this.ResourcePath.Split(["/"], StringSplitOptions.RemoveEmptyEntries);
             for (int i = 0; i < urlParts.Length; i++)
             {
                 string urlPart = urlParts[i];
@@ -103,13 +96,11 @@ public Uri CreateCommandUri(Uri baseUri, Command commandToExecute)
                 }
             }
 
-            Uri fullUri;
             string relativeUrlString = string.Join("/", urlParts);
             Uri relativeUri = new Uri(relativeUrlString, UriKind.Relative);
-            bool uriCreateSucceeded = Uri.TryCreate(baseUri, relativeUri, out fullUri);
-            if (!uriCreateSucceeded)
+            if (!Uri.TryCreate(baseUri, relativeUri, out Uri? fullUri))
             {
-                throw new InvalidOperationException(string.Format(CultureInfo.InvariantCulture, "Unable to create URI from base {0} and relative path {1}", baseUri == null ? string.Empty : baseUri.ToString(), relativeUrlString));
+                throw new InvalidOperationException(string.Format(CultureInfo.InvariantCulture, "Unable to create URI from base {0} and relative path {1}", baseUri?.ToString(), relativeUrlString));
             }
 
             return fullUri;
@@ -133,11 +124,11 @@ private static string GetCommandPropertyValue(string propertyName, Command comma
             {
                 // Extract the URL parameter, and remove it from the parameters dictionary
                 // so it doesn't get transmitted as a JSON parameter.
-                if (commandToExecute.Parameters.ContainsKey(propertyName))
+                if (commandToExecute.Parameters.TryGetValue(propertyName, out var propertyValueObject))
                 {
-                    if (commandToExecute.Parameters[propertyName] != null)
+                    if (propertyValueObject != null)
                     {
-                        propertyValue = commandToExecute.Parameters[propertyName].ToString();
+                        propertyValue = propertyValueObject.ToString()!;
                         commandToExecute.Parameters.Remove(propertyName);
                     }
                 }
diff --git a/dotnet/src/webdriver/ICommandExecutor.cs b/dotnet/src/webdriver/ICommandExecutor.cs
index e80d7ea63b10e..6fef4d9bf3ef1 100644
--- a/dotnet/src/webdriver/ICommandExecutor.cs
+++ b/dotnet/src/webdriver/ICommandExecutor.cs
@@ -18,8 +18,11 @@
 // </copyright>
 
 using System;
+using System.Diagnostics.CodeAnalysis;
 using System.Threading.Tasks;
 
+#nullable enable
+
 namespace OpenQA.Selenium
 {
     /// <summary>
@@ -31,15 +34,16 @@ public interface ICommandExecutor : IDisposable
         /// Attempts to add a command to the repository of commands known to this executor.
         /// </summary>
         /// <param name="commandName">The name of the command to attempt to add.</param>
-        /// <param name="info">The <see cref="CommandInfo"/> describing the commnd to add.</param>
+        /// <param name="info">The <see cref="CommandInfo"/> describing the command to add.</param>
         /// <returns><see langword="true"/> if the new command has been added successfully; otherwise, <see langword="false"/>.</returns>
-        bool TryAddCommand(string commandName, CommandInfo info);
+        bool TryAddCommand(string commandName, [NotNullWhen(true)] CommandInfo? info);
 
         /// <summary>
         /// Executes a command
         /// </summary>
         /// <param name="commandToExecute">The command you wish to execute</param>
         /// <returns>A response from the browser</returns>
+        /// <exception cref="ArgumentNullException">If <paramref name="commandToExecute"/> is <see langword="null"/>.</exception>
         Response Execute(Command commandToExecute);
 
 
@@ -48,6 +52,7 @@ public interface ICommandExecutor : IDisposable
         /// </summary>
         /// <param name="commandToExecute">The command you wish to execute</param>
         /// <returns>A task object representing the asynchronous operation</returns>
+        /// <exception cref="ArgumentNullException">If <paramref name="commandToExecute"/> is <see langword="null"/>.</exception>
         Task<Response> ExecuteAsync(Command commandToExecute);
     }
 }
diff --git a/dotnet/src/webdriver/ICustomDriverCommandExecutor.cs b/dotnet/src/webdriver/ICustomDriverCommandExecutor.cs
index 07f2169490391..145bb8c66013d 100644
--- a/dotnet/src/webdriver/ICustomDriverCommandExecutor.cs
+++ b/dotnet/src/webdriver/ICustomDriverCommandExecutor.cs
@@ -18,6 +18,9 @@
 // </copyright>
 
 using System.Collections.Generic;
+using System.Diagnostics.CodeAnalysis;
+
+#nullable enable
 
 namespace OpenQA.Selenium
 {
@@ -32,7 +35,8 @@ public interface ICustomDriverCommandExecutor
         /// <param name="driverCommandToExecute">The name of the command to execute. The command name must be registered with the command executor, and must not be a command name known to this driver type.</param>
         /// <param name="parameters">A <see cref="Dictionary{K, V}"/> containing the names and values of the parameters of the command.</param>
         /// <returns>An object that contains the value returned by the command, if any.</returns>
-        object ExecuteCustomDriverCommand(string driverCommandToExecute, Dictionary<string, object> parameters);
+        /// <exception cref="WebDriverException">The command returned an exceptional value.</exception>
+        object? ExecuteCustomDriverCommand(string driverCommandToExecute, Dictionary<string, object> parameters);
 
         /// <summary>
         /// Registers a set of commands to be executed with this driver instance.
@@ -46,6 +50,6 @@ public interface ICustomDriverCommandExecutor
         /// <param name="commandName">The unique name of the command to register.</param>
         /// <param name="commandInfo">The <see cref="CommandInfo"/> object describing the command.</param>
         /// <returns><see langword="true"/> if the command was registered; otherwise, <see langword="false"/>.</returns>
-        bool RegisterCustomDriverCommand(string commandName, CommandInfo commandInfo);
+        bool RegisterCustomDriverCommand(string commandName, [NotNullWhen(true)] CommandInfo? commandInfo);
     }
 }
diff --git a/dotnet/src/webdriver/Remote/DriverServiceCommandExecutor.cs b/dotnet/src/webdriver/Remote/DriverServiceCommandExecutor.cs
index b9bb4efcf0084..0f1d341c8c353 100644
--- a/dotnet/src/webdriver/Remote/DriverServiceCommandExecutor.cs
+++ b/dotnet/src/webdriver/Remote/DriverServiceCommandExecutor.cs
@@ -18,6 +18,7 @@
 // </copyright>
 
 using System;
+using System.Diagnostics.CodeAnalysis;
 using System.Threading.Tasks;
 
 #nullable enable
@@ -78,7 +79,7 @@ public DriverServiceCommandExecutor(DriverService service, HttpCommandExecutor c
         //    get { return this.HttpExecutor.CommandInfoRepository; }
         //}
 
-        public bool TryAddCommand(string commandName, CommandInfo info)
+        public bool TryAddCommand(string commandName, [NotNullWhen(true)] CommandInfo? info)
         {
             return this.HttpExecutor.TryAddCommand(commandName, info);
         }
@@ -94,6 +95,7 @@ public bool TryAddCommand(string commandName, CommandInfo info)
         /// </summary>
         /// <param name="commandToExecute">The command you wish to execute</param>
         /// <returns>A response from the browser</returns>
+        /// <exception cref="ArgumentNullException">If <paramref name="commandToExecute"/> is <see langword="null"/>.</exception>
         public Response Execute(Command commandToExecute)
         {
             return Task.Run(() => this.ExecuteAsync(commandToExecute)).GetAwaiter().GetResult();
@@ -104,6 +106,7 @@ public Response Execute(Command commandToExecute)
         /// </summary>
         /// <param name="commandToExecute">The command you wish to execute</param>
         /// <returns>A task object representing the asynchronous operation</returns>
+        /// <exception cref="ArgumentNullException">If <paramref name="commandToExecute"/> is <see langword="null"/>.</exception>
         public async Task<Response> ExecuteAsync(Command commandToExecute)
         {
             if (commandToExecute == null)
diff --git a/dotnet/src/webdriver/Remote/HttpCommandExecutor.cs b/dotnet/src/webdriver/Remote/HttpCommandExecutor.cs
index 9ab474b8ec235..2bcee9c7673ad 100644
--- a/dotnet/src/webdriver/Remote/HttpCommandExecutor.cs
+++ b/dotnet/src/webdriver/Remote/HttpCommandExecutor.cs
@@ -21,6 +21,7 @@
 using OpenQA.Selenium.Internal.Logging;
 using System;
 using System.Collections.Generic;
+using System.Diagnostics.CodeAnalysis;
 using System.Globalization;
 using System.Linq;
 using System.Net;
@@ -30,6 +31,8 @@
 using System.Threading;
 using System.Threading.Tasks;
 
+#nullable enable
+
 namespace OpenQA.Selenium.Remote
 {
     /// <summary>
@@ -47,7 +50,7 @@ public class HttpCommandExecutor : ICommandExecutor
         private readonly TimeSpan serverResponseTimeout;
         private bool isDisposed;
         private CommandInfoRepository commandInfoRepository = new W3CWireProtocolCommandInfoRepository();
-        private HttpClient client;
+        private readonly Lazy<HttpClient> client;
 
         private static readonly ILogger _logger = Log.GetLogger<HttpCommandExecutor>();
 
@@ -56,6 +59,7 @@ public class HttpCommandExecutor : ICommandExecutor
         /// </summary>
         /// <param name="addressOfRemoteServer">Address of the WebDriver Server</param>
         /// <param name="timeout">The timeout within which the server must respond.</param>
+        /// <exception cref="ArgumentNullException">If <paramref name="addressOfRemoteServer"/> is <see langword="null"/>.</exception>
         public HttpCommandExecutor(Uri addressOfRemoteServer, TimeSpan timeout)
             : this(addressOfRemoteServer, timeout, true)
         {
@@ -85,20 +89,21 @@ public HttpCommandExecutor(Uri addressOfRemoteServer, TimeSpan timeout, bool ena
             this.remoteServerUri = addressOfRemoteServer;
             this.serverResponseTimeout = timeout;
             this.IsKeepAliveEnabled = enableKeepAlive;
+            this.client = new Lazy<HttpClient>(CreateHttpClient);
         }
 
         /// <summary>
         /// Occurs when the <see cref="HttpCommandExecutor"/> is sending an HTTP
         /// request to the remote end WebDriver implementation.
         /// </summary>
-        public event EventHandler<SendingRemoteHttpRequestEventArgs> SendingRemoteHttpRequest;
+        public event EventHandler<SendingRemoteHttpRequestEventArgs>? SendingRemoteHttpRequest;
 
         /// <summary>
         /// Gets or sets an <see cref="IWebProxy"/> object to be used to proxy requests
         /// between this <see cref="HttpCommandExecutor"/> and the remote end WebDriver
         /// implementation.
         /// </summary>
-        public IWebProxy Proxy { get; set; }
+        public IWebProxy? Proxy { get; set; }
 
         /// <summary>
         /// Gets or sets a value indicating whether keep-alive is enabled for HTTP
@@ -109,7 +114,7 @@ public HttpCommandExecutor(Uri addressOfRemoteServer, TimeSpan timeout, bool ena
 
         /// <summary>
         /// Gets or sets the user agent string used for HTTP communication
-        /// batween this <see cref="HttpCommandExecutor"/> and the remote end
+        /// between this <see cref="HttpCommandExecutor"/> and the remote end
         /// WebDriver implementation
         /// </summary>
         public string UserAgent { get; set; }
@@ -128,9 +133,9 @@ protected CommandInfoRepository CommandInfoRepository
         /// Attempts to add a command to the repository of commands known to this executor.
         /// </summary>
         /// <param name="commandName">The name of the command to attempt to add.</param>
-        /// <param name="info">The <see cref="CommandInfo"/> describing the commnd to add.</param>
+        /// <param name="info">The <see cref="CommandInfo"/> describing the command to add.</param>
         /// <returns><see langword="true"/> if the new command has been added successfully; otherwise, <see langword="false"/>.</returns>
-        public bool TryAddCommand(string commandName, CommandInfo info)
+        public bool TryAddCommand(string commandName, [NotNullWhen(true)] CommandInfo? info)
         {
             if (info is not HttpCommandInfo commandInfo)
             {
@@ -145,6 +150,7 @@ public bool TryAddCommand(string commandName, CommandInfo info)
         /// </summary>
         /// <param name="commandToExecute">The command you wish to execute.</param>
         /// <returns>A response from the browser.</returns>
+        /// <exception cref="ArgumentNullException">If <paramref name="commandToExecute"/> is <see langword="null"/>.</exception>
         public virtual Response Execute(Command commandToExecute)
         {
             return Task.Run(() => this.ExecuteAsync(commandToExecute)).GetAwaiter().GetResult();
@@ -155,6 +161,7 @@ public virtual Response Execute(Command commandToExecute)
         /// </summary>
         /// <param name="commandToExecute">The command you wish to execute.</param>
         /// <returns>A task object representing the asynchronous operation.</returns>
+        /// <exception cref="ArgumentNullException">If <paramref name="commandToExecute"/> is <see langword="null"/>.</exception>
         public virtual async Task<Response> ExecuteAsync(Command commandToExecute)
         {
             if (commandToExecute == null)
@@ -164,20 +171,15 @@ public virtual async Task<Response> ExecuteAsync(Command commandToExecute)
 
             if (_logger.IsEnabled(LogEventLevel.Debug))
             {
-                _logger.Debug($"Executing command: {commandToExecute}");
+                _logger.Debug($"Executing command: [{commandToExecute.SessionId}]: {commandToExecute.Name}");
             }
 
-            HttpCommandInfo info = this.commandInfoRepository.GetCommandInfo<HttpCommandInfo>(commandToExecute.Name);
+            HttpCommandInfo? info = this.commandInfoRepository.GetCommandInfo<HttpCommandInfo>(commandToExecute.Name);
             if (info == null)
             {
                 throw new NotImplementedException(string.Format("The command you are attempting to execute, {0}, does not exist in the protocol dialect used by the remote end.", commandToExecute.Name));
             }
 
-            if (this.client == null)
-            {
-                this.CreateHttpClient();
-            }
-
             HttpRequestInfo requestInfo = new HttpRequestInfo(this.remoteServerUri, commandToExecute, info);
             HttpResponseInfo responseInfo;
             try
@@ -216,13 +218,10 @@ protected virtual void OnSendingRemoteHttpRequest(SendingRemoteHttpRequestEventA
                 throw new ArgumentNullException(nameof(eventArgs), "eventArgs must not be null");
             }
 
-            if (this.SendingRemoteHttpRequest != null)
-            {
-                this.SendingRemoteHttpRequest(this, eventArgs);
-            }
+            this.SendingRemoteHttpRequest?.Invoke(this, eventArgs);
         }
 
-        private void CreateHttpClient()
+        private HttpClient CreateHttpClient()
         {
             HttpClientHandler httpClientHandler = new HttpClientHandler();
             string userInfo = this.remoteServerUri.UserInfo;
@@ -242,16 +241,17 @@ private void CreateHttpClient()
                 handler = new DiagnosticsHttpHandler(httpClientHandler, _logger);
             }
 
-            this.client = new HttpClient(handler);
-            this.client.DefaultRequestHeaders.UserAgent.ParseAdd(this.UserAgent);
-            this.client.DefaultRequestHeaders.Accept.ParseAdd(RequestAcceptHeader);
-            this.client.DefaultRequestHeaders.ExpectContinue = false;
+            var client = new HttpClient(handler);
+            client.DefaultRequestHeaders.UserAgent.ParseAdd(this.UserAgent);
+            client.DefaultRequestHeaders.Accept.ParseAdd(RequestAcceptHeader);
+            client.DefaultRequestHeaders.ExpectContinue = false;
             if (!this.IsKeepAliveEnabled)
             {
-                this.client.DefaultRequestHeaders.Connection.ParseAdd("close");
+                client.DefaultRequestHeaders.Connection.ParseAdd("close");
             }
 
-            this.client.Timeout = this.serverResponseTimeout;
+            client.Timeout = this.serverResponseTimeout;
+            return client;
         }
 
         private async Task<HttpResponseInfo> MakeHttpRequest(HttpRequestInfo requestInfo)
@@ -288,7 +288,7 @@ private async Task<HttpResponseInfo> MakeHttpRequest(HttpRequestInfo requestInfo
                     requestMessage.Content.Headers.ContentType = contentTypeHeader;
                 }
 
-                using (HttpResponseMessage responseMessage = await this.client.SendAsync(requestMessage).ConfigureAwait(false))
+                using (HttpResponseMessage responseMessage = await this.client.Value.SendAsync(requestMessage).ConfigureAwait(false))
                 {
                     var responseBody = await responseMessage.Content.ReadAsStringAsync().ConfigureAwait(false);
                     var responseContentType = responseMessage.Content.Headers.ContentType?.ToString();
@@ -332,8 +332,6 @@ private Response CreateResponse(HttpResponseInfo responseInfo)
             return response;
         }
 
-#nullable enable
-
         /// <summary>
         /// Releases all resources used by the <see cref="HttpCommandExecutor"/>.
         /// </summary>
@@ -353,7 +351,10 @@ protected virtual void Dispose(bool disposing)
         {
             if (!this.isDisposed)
             {
-                this.client?.Dispose();
+                if (this.client.IsValueCreated)
+                {
+                    this.client.Value.Dispose();
+                }
 
                 this.isDisposed = true;
             }
diff --git a/dotnet/src/webdriver/WebDriver.cs b/dotnet/src/webdriver/WebDriver.cs
index 974cbf608fcba..b5e8d5b6437b5 100644
--- a/dotnet/src/webdriver/WebDriver.cs
+++ b/dotnet/src/webdriver/WebDriver.cs
@@ -463,13 +463,16 @@ public INavigation Navigate()
             return new Navigator(this);
         }
 
+#nullable enable
+
         /// <summary>
         /// Executes a command with this driver.
         /// </summary>
         /// <param name="driverCommandToExecute">The name of the command to execute. The command name must be registered with the command executor, and must not be a command name known to this driver type.</param>
         /// <param name="parameters">A <see cref="Dictionary{K, V}"/> containing the names and values of the parameters of the command.</param>
         /// <returns>A <see cref="Response"/> containing information about the success or failure of the command and any data returned by the command.</returns>
-        public object ExecuteCustomDriverCommand(string driverCommandToExecute, Dictionary<string, object> parameters)
+        /// <exception cref="WebDriverException">The command returned an exceptional value.</exception>
+        public object? ExecuteCustomDriverCommand(string driverCommandToExecute, Dictionary<string, object> parameters)
         {
             if (this.registeredCommands.Contains(driverCommandToExecute))
             {
@@ -497,7 +500,7 @@ public void RegisterCustomDriverCommands(IReadOnlyDictionary<string, CommandInfo
         /// <param name="commandName">The unique name of the command to register.</param>
         /// <param name="commandInfo">The <see cref="CommandInfo"/> object describing the command.</param>
         /// <returns><see langword="true"/> if the command was registered; otherwise, <see langword="false"/>.</returns>
-        public bool RegisterCustomDriverCommand(string commandName, CommandInfo commandInfo)
+        public bool RegisterCustomDriverCommand(string commandName, [NotNullWhen(true)] CommandInfo? commandInfo)
         {
             return this.RegisterDriverCommand(commandName, commandInfo, false);
         }
@@ -509,17 +512,23 @@ public bool RegisterCustomDriverCommand(string commandName, CommandInfo commandI
         /// <param name="commandInfo">The <see cref="CommandInfo"/> object describing the command.</param>
         /// <param name="isInternalCommand"><see langword="true"/> if the registered command is internal to the driver; otherwise <see langword="false"/>.</param>
         /// <returns><see langword="true"/> if the command was registered; otherwise, <see langword="false"/>.</returns>
-        internal bool RegisterDriverCommand(string commandName, CommandInfo commandInfo, bool isInternalCommand)
+        internal bool RegisterDriverCommand(string commandName, [NotNullWhen(true)] CommandInfo? commandInfo, bool isInternalCommand)
         {
-            bool commandAdded = this.CommandExecutor.TryAddCommand(commandName, commandInfo);
-            if (commandAdded && isInternalCommand)
+            if (this.CommandExecutor.TryAddCommand(commandName, commandInfo))
             {
-                this.registeredCommands.Add(commandName);
+                if (isInternalCommand)
+                {
+                    this.registeredCommands.Add(commandName);
+                }
+
+                return true;
             }
 
-            return commandAdded;
+            return false;
         }
 
+#nullable restore
+
         /// <summary>
         /// Find the element in the response
         /// </summary>
@@ -692,17 +701,21 @@ protected virtual Dictionary<string, object> GetCapabilitiesDictionary(ICapabili
             return capabilitiesDictionary;
         }
 
+#nullable enable
+
         /// <summary>
         /// Registers a command to be executed with this driver instance as an internally known driver command.
         /// </summary>
         /// <param name="commandName">The unique name of the command to register.</param>
         /// <param name="commandInfo">The <see cref="CommandInfo"/> object describing the command.</param>
         /// <returns><see langword="true"/> if the command was registered; otherwise, <see langword="false"/>.</returns>
-        protected bool RegisterInternalDriverCommand(string commandName, CommandInfo commandInfo)
+        protected bool RegisterInternalDriverCommand(string commandName, [NotNullWhen(true)] CommandInfo? commandInfo)
         {
             return this.RegisterDriverCommand(commandName, commandInfo, true);
         }
 
+#nullable restore
+
         /// <summary>
         /// Stops the client from running
         /// </summary>