diff --git a/Emby.Server.Implementations/AppBase/BaseConfigurationManager.cs b/Emby.Server.Implementations/AppBase/BaseConfigurationManager.cs
index 2a4a8fb132..c42cec593a 100644
--- a/Emby.Server.Implementations/AppBase/BaseConfigurationManager.cs
+++ b/Emby.Server.Implementations/AppBase/BaseConfigurationManager.cs
@@ -365,11 +365,7 @@ namespace Emby.Server.Implementations.AppBase
                 validatingStore.Validate(currentConfiguration, configuration);
             }
 
-            NamedConfigurationUpdating?.Invoke(this, new ConfigurationUpdateEventArgs
-            {
-                Key = key,
-                NewConfiguration = configuration
-            });
+            NamedConfigurationUpdating?.Invoke(this, new ConfigurationUpdateEventArgs(key, configuration));
 
             _configurations.AddOrUpdate(key, configuration, (_, _) => configuration);
 
@@ -391,11 +387,7 @@ namespace Emby.Server.Implementations.AppBase
         /// <param name="configuration">The old configuration.</param>
         protected virtual void OnNamedConfigurationUpdated(string key, object configuration)
         {
-            NamedConfigurationUpdated?.Invoke(this, new ConfigurationUpdateEventArgs
-            {
-                Key = key,
-                NewConfiguration = configuration
-            });
+            NamedConfigurationUpdated?.Invoke(this, new ConfigurationUpdateEventArgs(key, configuration));
         }
 
         /// <inheritdoc />
diff --git a/Jellyfin.Api/Attributes/HttpSubscribeAttribute.cs b/Jellyfin.Api/Attributes/HttpSubscribeAttribute.cs
index af8727552c..7ac089a344 100644
--- a/Jellyfin.Api/Attributes/HttpSubscribeAttribute.cs
+++ b/Jellyfin.Api/Attributes/HttpSubscribeAttribute.cs
@@ -25,11 +25,6 @@ namespace Jellyfin.Api.Attributes
         /// <param name="template">The route template. May not be null.</param>
         public HttpSubscribeAttribute(string template)
             : base(_supportedMethods, template)
-        {
-            if (template == null)
-            {
-                throw new ArgumentNullException(nameof(template));
-            }
-        }
+            => ArgumentNullException.ThrowIfNull(template, nameof(template));
     }
 }
diff --git a/Jellyfin.Api/Attributes/HttpUnsubscribeAttribute.cs b/Jellyfin.Api/Attributes/HttpUnsubscribeAttribute.cs
index 1c0b70e719..16b3d08160 100644
--- a/Jellyfin.Api/Attributes/HttpUnsubscribeAttribute.cs
+++ b/Jellyfin.Api/Attributes/HttpUnsubscribeAttribute.cs
@@ -25,11 +25,6 @@ namespace Jellyfin.Api.Attributes
         /// <param name="template">The route template. May not be null.</param>
         public HttpUnsubscribeAttribute(string template)
             : base(_supportedMethods, template)
-        {
-            if (template == null)
-            {
-                throw new ArgumentNullException(nameof(template));
-            }
-        }
+            => ArgumentNullException.ThrowIfNull(template, nameof(template));
     }
 }
diff --git a/Jellyfin.Api/Controllers/DisplayPreferencesController.cs b/Jellyfin.Api/Controllers/DisplayPreferencesController.cs
index 27eb223390..64ee5680ce 100644
--- a/Jellyfin.Api/Controllers/DisplayPreferencesController.cs
+++ b/Jellyfin.Api/Controllers/DisplayPreferencesController.cs
@@ -89,12 +89,9 @@ namespace Jellyfin.Api.Controllers
 
             // Load all custom display preferences
             var customDisplayPreferences = _displayPreferencesManager.ListCustomItemDisplayPreferences(displayPreferences.UserId, itemId, displayPreferences.Client);
-            if (customDisplayPreferences != null)
+            foreach (var (key, value) in customDisplayPreferences)
             {
-                foreach (var (key, value) in customDisplayPreferences)
-                {
-                    dto.CustomPrefs.TryAdd(key, value);
-                }
+                dto.CustomPrefs.TryAdd(key, value);
             }
 
             // This will essentially be a noop if no changes have been made, but new prefs must be saved at least.
diff --git a/Jellyfin.Drawing.Skia/SkiaEncoder.cs b/Jellyfin.Drawing.Skia/SkiaEncoder.cs
index 6875282318..13f155f357 100644
--- a/Jellyfin.Drawing.Skia/SkiaEncoder.cs
+++ b/Jellyfin.Drawing.Skia/SkiaEncoder.cs
@@ -145,9 +145,11 @@ namespace Jellyfin.Drawing.Skia
         /// <exception cref="SkiaCodecException">The file at the specified path could not be used to generate a codec.</exception>
         public string GetImageBlurHash(int xComp, int yComp, string path)
         {
-            if (path == null)
+            ArgumentNullException.ThrowIfNull(path, nameof(path));
+
+            if (path.Length == 0)
             {
-                throw new ArgumentNullException(nameof(path));
+                throw new ArgumentException("String can't be empty", nameof(path));
             }
 
             var extension = Path.GetExtension(path.AsSpan()).TrimStart('.');
diff --git a/Jellyfin.Server.Implementations/Users/DisplayPreferencesManager.cs b/Jellyfin.Server.Implementations/Users/DisplayPreferencesManager.cs
index f5d38db20f..65edb30ad2 100644
--- a/Jellyfin.Server.Implementations/Users/DisplayPreferencesManager.cs
+++ b/Jellyfin.Server.Implementations/Users/DisplayPreferencesManager.cs
@@ -79,7 +79,7 @@ namespace Jellyfin.Server.Implementations.Users
         }
 
         /// <inheritdoc />
-        public void SetCustomItemDisplayPreferences(Guid userId, Guid itemId, string client, Dictionary<string, string> customPreferences)
+        public void SetCustomItemDisplayPreferences(Guid userId, Guid itemId, string client, Dictionary<string, string?> customPreferences)
         {
             var existingPrefs = _dbContext.CustomItemDisplayPreferences
                 .AsQueryable()
diff --git a/Jellyfin.Server/Infrastructure/SymlinkFollowingPhysicalFileResultExecutor.cs b/Jellyfin.Server/Infrastructure/SymlinkFollowingPhysicalFileResultExecutor.cs
index 7e7e4ca95b..28ed3894fd 100644
--- a/Jellyfin.Server/Infrastructure/SymlinkFollowingPhysicalFileResultExecutor.cs
+++ b/Jellyfin.Server/Infrastructure/SymlinkFollowingPhysicalFileResultExecutor.cs
@@ -69,15 +69,8 @@ namespace Jellyfin.Server.Infrastructure
         /// <inheritdoc />
         protected override Task WriteFileAsync(ActionContext context, PhysicalFileResult result, RangeItemHeaderValue? range, long rangeLength)
         {
-            if (context == null)
-            {
-                throw new ArgumentNullException(nameof(context));
-            }
-
-            if (result == null)
-            {
-                throw new ArgumentNullException(nameof(result));
-            }
+            ArgumentNullException.ThrowIfNull(context, nameof(context));
+            ArgumentNullException.ThrowIfNull(result, nameof(result));
 
             if (range != null && rangeLength == 0)
             {
diff --git a/MediaBrowser.Common/Configuration/ConfigurationUpdateEventArgs.cs b/MediaBrowser.Common/Configuration/ConfigurationUpdateEventArgs.cs
index 2df87d8792..90b1ff70c2 100644
--- a/MediaBrowser.Common/Configuration/ConfigurationUpdateEventArgs.cs
+++ b/MediaBrowser.Common/Configuration/ConfigurationUpdateEventArgs.cs
@@ -1,22 +1,33 @@
-#nullable disable
-#pragma warning disable CS1591
-
 using System;
 
 namespace MediaBrowser.Common.Configuration
 {
+    /// <summary>
+    /// <see cref="EventArgs" /> for the ConfigurationUpdated event.
+    /// </summary>
     public class ConfigurationUpdateEventArgs : EventArgs
     {
         /// <summary>
-        /// Gets or sets the key.
+        /// Initializes a new instance of the <see cref="ConfigurationUpdateEventArgs"/> class.
+        /// </summary>
+        /// <param name="key">The configuration key.</param>
+        /// <param name="newConfiguration">The new configuration.</param>
+        public ConfigurationUpdateEventArgs(string key, object newConfiguration)
+        {
+            Key = key;
+            NewConfiguration = newConfiguration;
+        }
+
+        /// <summary>
+        /// Gets the key.
         /// </summary>
         /// <value>The key.</value>
-        public string Key { get; set; }
+        public string Key { get; }
 
         /// <summary>
-        /// Gets or sets the new configuration.
+        /// Gets the new configuration.
         /// </summary>
         /// <value>The new configuration.</value>
-        public object NewConfiguration { get; set; }
+        public object NewConfiguration { get; }
     }
 }
diff --git a/MediaBrowser.Common/Configuration/IApplicationPaths.cs b/MediaBrowser.Common/Configuration/IApplicationPaths.cs
index 1370e6d79e..57c6546675 100644
--- a/MediaBrowser.Common/Configuration/IApplicationPaths.cs
+++ b/MediaBrowser.Common/Configuration/IApplicationPaths.cs
@@ -1,5 +1,3 @@
-#nullable disable
-
 namespace MediaBrowser.Common.Configuration
 {
     /// <summary>
diff --git a/MediaBrowser.Controller/Entities/BasePluginFolder.cs b/MediaBrowser.Controller/Entities/BasePluginFolder.cs
index 272a37df1b..afafaf1c24 100644
--- a/MediaBrowser.Controller/Entities/BasePluginFolder.cs
+++ b/MediaBrowser.Controller/Entities/BasePluginFolder.cs
@@ -1,5 +1,3 @@
-#nullable disable
-
 #pragma warning disable CS1591
 
 using System.Text.Json.Serialization;
@@ -13,7 +11,7 @@ namespace MediaBrowser.Controller.Entities
     public abstract class BasePluginFolder : Folder, ICollectionFolder
     {
         [JsonIgnore]
-        public virtual string CollectionType => null;
+        public virtual string? CollectionType => null;
 
         [JsonIgnore]
         public override bool SupportsInheritedParentImages => false;
diff --git a/MediaBrowser.Controller/Entities/Extensions.cs b/MediaBrowser.Controller/Entities/Extensions.cs
index 9ce8eebe34..14534aa50b 100644
--- a/MediaBrowser.Controller/Entities/Extensions.cs
+++ b/MediaBrowser.Controller/Entities/Extensions.cs
@@ -1,5 +1,3 @@
-#nullable disable
-
 using System;
 using System.Linq;
 using Jellyfin.Extensions;
@@ -19,9 +17,11 @@ namespace MediaBrowser.Controller.Entities
         /// <param name="url">Trailer URL.</param>
         public static void AddTrailerUrl(this BaseItem item, string url)
         {
-            if (string.IsNullOrEmpty(url))
+            ArgumentNullException.ThrowIfNull(url, nameof(url));
+
+            if (url.Length == 0)
             {
-                throw new ArgumentNullException(nameof(url));
+                throw new ArgumentException("String can't be empty", nameof(url));
             }
 
             var current = item.RemoteTrailers.FirstOrDefault(i => string.Equals(i.Url, url, StringComparison.OrdinalIgnoreCase));
diff --git a/MediaBrowser.Controller/IDisplayPreferencesManager.cs b/MediaBrowser.Controller/IDisplayPreferencesManager.cs
index 1678d50675..10c0f56e09 100644
--- a/MediaBrowser.Controller/IDisplayPreferencesManager.cs
+++ b/MediaBrowser.Controller/IDisplayPreferencesManager.cs
@@ -1,5 +1,3 @@
-#nullable disable
-
 using System;
 using System.Collections.Generic;
 using Jellyfin.Data.Entities;
@@ -50,7 +48,7 @@ namespace MediaBrowser.Controller
         /// <param name="itemId">The item id.</param>
         /// <param name="client">The client string.</param>
         /// <returns>The dictionary of custom item display preferences.</returns>
-        Dictionary<string, string> ListCustomItemDisplayPreferences(Guid userId, Guid itemId, string client);
+        Dictionary<string, string?> ListCustomItemDisplayPreferences(Guid userId, Guid itemId, string client);
 
         /// <summary>
         /// Sets the custom item display preference for the user and client.
@@ -59,7 +57,7 @@ namespace MediaBrowser.Controller
         /// <param name="itemId">The item id.</param>
         /// <param name="client">The client id.</param>
         /// <param name="customPreferences">A dictionary of custom item display preferences.</param>
-        void SetCustomItemDisplayPreferences(Guid userId, Guid itemId, string client, Dictionary<string, string> customPreferences);
+        void SetCustomItemDisplayPreferences(Guid userId, Guid itemId, string client, Dictionary<string, string?> customPreferences);
 
         /// <summary>
         /// Saves changes made to the database.