diff --git a/src/Microsoft.Azure.AppConfiguration.AspNetCore/AzureAppConfigurationRefreshExtensions.cs b/src/Microsoft.Azure.AppConfiguration.AspNetCore/AzureAppConfigurationRefreshExtensions.cs
index 671c98400..523fba9e4 100644
--- a/src/Microsoft.Azure.AppConfiguration.AspNetCore/AzureAppConfigurationRefreshExtensions.cs
+++ b/src/Microsoft.Azure.AppConfiguration.AspNetCore/AzureAppConfigurationRefreshExtensions.cs
@@ -25,7 +25,7 @@ public static IApplicationBuilder UseAzureAppConfiguration(this IApplicationBuil
                 throw new ArgumentNullException(nameof(builder));
             }
 
-            IConfigurationRefresherProvider refresherProvider = (IConfigurationRefresherProvider)builder.ApplicationServices.GetService(typeof(IConfigurationRefresherProvider));
+            IConfigurationRefresherProvider? refresherProvider = (IConfigurationRefresherProvider?)builder.ApplicationServices.GetService(typeof(IConfigurationRefresherProvider));
 
             // Verify if AddAzureAppConfiguration was done before calling UseAzureAppConfiguration.
             // We use the IConfigurationRefresherProvider to make sure if the required services were added.
diff --git a/src/Microsoft.Azure.AppConfiguration.AspNetCore/Microsoft.Azure.AppConfiguration.AspNetCore.csproj b/src/Microsoft.Azure.AppConfiguration.AspNetCore/Microsoft.Azure.AppConfiguration.AspNetCore.csproj
index 72e540879..8b64421ab 100644
--- a/src/Microsoft.Azure.AppConfiguration.AspNetCore/Microsoft.Azure.AppConfiguration.AspNetCore.csproj
+++ b/src/Microsoft.Azure.AppConfiguration.AspNetCore/Microsoft.Azure.AppConfiguration.AspNetCore.csproj
@@ -3,6 +3,7 @@
 
   <PropertyGroup>
     <TargetFrameworks>net8.0;net9.0</TargetFrameworks>
+    <Nullable>enable</Nullable>
     <Description>Microsoft.Azure.AppConfiguration.AspNetCore allows developers to use Microsoft Azure App Configuration service as a configuration source in their applications. This package adds additional features for ASP.NET Core applications to the existing package Microsoft.Extensions.Configuration.AzureAppConfiguration.</Description>
     <SignAssembly>true</SignAssembly>
     <DelaySign>false</DelaySign>
diff --git a/src/Microsoft.Azure.AppConfiguration.Functions.Worker/AzureAppConfigurationRefreshExtensions.cs b/src/Microsoft.Azure.AppConfiguration.Functions.Worker/AzureAppConfigurationRefreshExtensions.cs
index 2623d59c3..a167a74a4 100644
--- a/src/Microsoft.Azure.AppConfiguration.Functions.Worker/AzureAppConfigurationRefreshExtensions.cs
+++ b/src/Microsoft.Azure.AppConfiguration.Functions.Worker/AzureAppConfigurationRefreshExtensions.cs
@@ -24,7 +24,7 @@ public static class AzureAppConfigurationRefreshExtensions
         public static IFunctionsWorkerApplicationBuilder UseAzureAppConfiguration(this IFunctionsWorkerApplicationBuilder builder)
         {
             IServiceProvider serviceProvider = builder.Services.BuildServiceProvider();
-            IConfigurationRefresherProvider refresherProvider = serviceProvider.GetService<IConfigurationRefresherProvider>();
+            IConfigurationRefresherProvider? refresherProvider = serviceProvider.GetService<IConfigurationRefresherProvider>();
 
             // Verify if AddAzureAppConfiguration was done before calling UseAzureAppConfiguration.
             // We use the IConfigurationRefresherProvider to make sure if the required services were added.
diff --git a/src/Microsoft.Azure.AppConfiguration.Functions.Worker/Microsoft.Azure.AppConfiguration.Functions.Worker.csproj b/src/Microsoft.Azure.AppConfiguration.Functions.Worker/Microsoft.Azure.AppConfiguration.Functions.Worker.csproj
index 2531bbe3e..5300ea1ff 100644
--- a/src/Microsoft.Azure.AppConfiguration.Functions.Worker/Microsoft.Azure.AppConfiguration.Functions.Worker.csproj
+++ b/src/Microsoft.Azure.AppConfiguration.Functions.Worker/Microsoft.Azure.AppConfiguration.Functions.Worker.csproj
@@ -3,6 +3,7 @@
 
   <PropertyGroup>
     <TargetFrameworks>net8.0;net9.0</TargetFrameworks>
+    <Nullable>enable</Nullable>
     <Description>Microsoft.Azure.AppConfiguration.Functions.Worker allows developers to use the Microsoft Azure App Configuration service as a configuration source in their applications. This package adds additional features to the existing package Microsoft.Extensions.Configuration.AzureAppConfiguration for .NET Azure Functions running in an isolated process.</Description>
     <SignAssembly>true</SignAssembly>
     <DelaySign>false</DelaySign>
diff --git a/src/Microsoft.Extensions.Configuration.AzureAppConfiguration/AzureAppConfigurationKeyVaultOptions.cs b/src/Microsoft.Extensions.Configuration.AzureAppConfiguration/AzureAppConfigurationKeyVaultOptions.cs
index cca16df80..880efc2f4 100644
--- a/src/Microsoft.Extensions.Configuration.AzureAppConfiguration/AzureAppConfigurationKeyVaultOptions.cs
+++ b/src/Microsoft.Extensions.Configuration.AzureAppConfiguration/AzureAppConfigurationKeyVaultOptions.cs
@@ -18,7 +18,7 @@ public class AzureAppConfigurationKeyVaultOptions
         // This allows the provider to throw a KeyVaultReferenceException with all relevant information and halt startup instead of timing out.
         private const int KeyVaultMaxRetries = 6;
 
-        internal TokenCredential Credential;
+        internal TokenCredential? Credential;
         internal SecretClientOptions ClientOptions = new SecretClientOptions
         {
             Retry = {
@@ -26,7 +26,7 @@ public class AzureAppConfigurationKeyVaultOptions
             }
         };
         internal List<SecretClient> SecretClients = new List<SecretClient>();
-        internal Func<Uri, ValueTask<string>> SecretResolver;
+        internal Func<Uri, ValueTask<string>>? SecretResolver;
         internal Dictionary<string, TimeSpan> SecretRefreshIntervals = new Dictionary<string, TimeSpan>();
         internal TimeSpan? DefaultSecretRefreshInterval = null;
         internal bool IsKeyVaultRefreshConfigured = false;
diff --git a/src/Microsoft.Extensions.Configuration.AzureAppConfiguration/AzureAppConfigurationOptions.cs b/src/Microsoft.Extensions.Configuration.AzureAppConfiguration/AzureAppConfigurationOptions.cs
index e5b6e2585..9a7e94a7b 100644
--- a/src/Microsoft.Extensions.Configuration.AzureAppConfiguration/AzureAppConfigurationOptions.cs
+++ b/src/Microsoft.Extensions.Configuration.AzureAppConfiguration/AzureAppConfigurationOptions.cs
@@ -51,19 +51,19 @@ public class AzureAppConfigurationOptions
         /// <summary>
         /// The list of connection strings used to connect to an Azure App Configuration store and its replicas.
         /// </summary>
-        internal IEnumerable<string> ConnectionStrings { get; private set; }
+        internal IEnumerable<string>? ConnectionStrings { get; private set; }
 
         /// <summary>
         /// The list of endpoints of an Azure App Configuration store.
         /// If this property is set, the <see cref="Credential"/> property also needs to be set.
         /// </summary>
-        internal IEnumerable<Uri> Endpoints { get; private set; }
+        internal IEnumerable<Uri>? Endpoints { get; private set; }
 
         /// <summary>
         /// The credential used to connect to the Azure App Configuration.
         /// If this property is set, the <see cref="Endpoints"/> property also needs to be set.
         /// </summary>
-        internal TokenCredential Credential { get; private set; }
+        internal TokenCredential? Credential { get; private set; }
 
         /// <summary>
         /// A collection of <see cref="KeyValueSelector"/> specified by user.
@@ -96,7 +96,7 @@ public class AzureAppConfigurationOptions
         internal IEnumerable<IKeyValueAdapter> Adapters
         {
             get => _adapters;
-            set => _adapters = value?.ToList();
+            set => _adapters = value?.ToList() ?? new List<IKeyValueAdapter>();
         }
 
         /// <summary>
@@ -112,17 +112,17 @@ internal IEnumerable<IKeyValueAdapter> Adapters
         /// <summary>
         /// For use in tests only. An optional configuration client manager that can be used to provide clients to communicate with Azure App Configuration.
         /// </summary>
-        internal IConfigurationClientManager ClientManager { get; set; }
+        internal IConfigurationClientManager? ClientManager { get; set; }
 
         /// <summary>
         /// For use in tests only. An optional class used to process pageable results from Azure App Configuration.
         /// </summary>
-        internal IConfigurationSettingPageIterator ConfigurationSettingPageIterator { get; set; }
+        internal IConfigurationSettingPageIterator? ConfigurationSettingPageIterator { get; set; }
 
         /// <summary>
         /// For use in tests only. An optional activity source name to specify the activity source used by the configuration provider.
         /// </summary>
-        internal string ActivitySourceName { get; set; }
+        internal string? ActivitySourceName { get; set; }
 
         /// <summary>
         /// An optional timespan value to set the minimum backoff duration to a value other than the default.
@@ -157,7 +157,7 @@ internal IEnumerable<IKeyValueAdapter> Adapters
         /// <summary>
         /// Client factory that is responsible for creating instances of ConfigurationClient.
         /// </summary>
-        internal IAzureClientFactory<ConfigurationClient> ClientFactory { get; private set; }
+        internal IAzureClientFactory<ConfigurationClient>? ClientFactory { get; private set; }
 
         /// <summary>
         /// Initializes a new instance of the <see cref="AzureAppConfigurationOptions"/> class.
@@ -215,7 +215,7 @@ public AzureAppConfigurationOptions SetClientFactory(IAzureClientFactory<Configu
         /// The characters asterisk (*), comma (,) and backslash (\) are reserved and must be escaped using a backslash (\).
         /// Up to 5 tag filters can be provided. If no tag filters are provided, key-values will not be filtered based on tags.
         /// </param>
-        public AzureAppConfigurationOptions Select(string keyFilter, string labelFilter = LabelFilter.Null, IEnumerable<string> tagFilters = null)
+        public AzureAppConfigurationOptions Select(string keyFilter, string labelFilter = LabelFilter.Null, IEnumerable<string>? tagFilters = null)
         {
             if (string.IsNullOrEmpty(keyFilter))
             {
diff --git a/src/Microsoft.Extensions.Configuration.AzureAppConfiguration/AzureAppConfigurationProvider.cs b/src/Microsoft.Extensions.Configuration.AzureAppConfiguration/AzureAppConfigurationProvider.cs
index fc92d1290..23f0a5df5 100644
--- a/src/Microsoft.Extensions.Configuration.AzureAppConfiguration/AzureAppConfigurationProvider.cs
+++ b/src/Microsoft.Extensions.Configuration.AzureAppConfiguration/AzureAppConfigurationProvider.cs
@@ -1,6 +1,7 @@
 // Copyright (c) Microsoft Corporation.
 // Licensed under the MIT license.
 //
+#nullable disable
 using Azure;
 using Azure.Data.AppConfiguration;
 using Microsoft.Extensions.Configuration.AzureAppConfiguration.SnapshotReference;
diff --git a/src/Microsoft.Extensions.Configuration.AzureAppConfiguration/AzureAppConfigurationSource.cs b/src/Microsoft.Extensions.Configuration.AzureAppConfiguration/AzureAppConfigurationSource.cs
index 83d20e2fb..f26894de2 100644
--- a/src/Microsoft.Extensions.Configuration.AzureAppConfiguration/AzureAppConfigurationSource.cs
+++ b/src/Microsoft.Extensions.Configuration.AzureAppConfiguration/AzureAppConfigurationSource.cs
@@ -28,7 +28,7 @@ public AzureAppConfigurationSource(Action<AzureAppConfigurationOptions> optionsI
 
         public IConfigurationProvider Build(IConfigurationBuilder builder)
         {
-            IConfigurationProvider provider = null;
+            IConfigurationProvider? provider = null;
 
             try
             {
diff --git a/src/Microsoft.Extensions.Configuration.AzureAppConfiguration/AzureKeyVaultReference/AzureKeyVaultKeyValueAdapter.cs b/src/Microsoft.Extensions.Configuration.AzureAppConfiguration/AzureKeyVaultReference/AzureKeyVaultKeyValueAdapter.cs
index 0498ba09e..0bd23175f 100644
--- a/src/Microsoft.Extensions.Configuration.AzureAppConfiguration/AzureKeyVaultReference/AzureKeyVaultKeyValueAdapter.cs
+++ b/src/Microsoft.Extensions.Configuration.AzureAppConfiguration/AzureKeyVaultReference/AzureKeyVaultKeyValueAdapter.cs
@@ -1,6 +1,7 @@
 // Copyright (c) Microsoft Corporation.
 // Licensed under the MIT license.
 //
+#nullable disable
 using Azure;
 using Azure.Data.AppConfiguration;
 using Azure.Security.KeyVault.Secrets;
diff --git a/src/Microsoft.Extensions.Configuration.AzureAppConfiguration/AzureKeyVaultReference/AzureKeyVaultSecretProvider.cs b/src/Microsoft.Extensions.Configuration.AzureAppConfiguration/AzureKeyVaultReference/AzureKeyVaultSecretProvider.cs
index 57505ff95..762d384a4 100644
--- a/src/Microsoft.Extensions.Configuration.AzureAppConfiguration/AzureKeyVaultReference/AzureKeyVaultSecretProvider.cs
+++ b/src/Microsoft.Extensions.Configuration.AzureAppConfiguration/AzureKeyVaultReference/AzureKeyVaultSecretProvider.cs
@@ -1,6 +1,7 @@
 // Copyright (c) Microsoft Corporation.
 // Licensed under the MIT license.
 //
+#nullable disable
 using Azure.Security.KeyVault.Secrets;
 using Microsoft.Extensions.Configuration.AzureAppConfiguration.Extensions;
 using System;
diff --git a/src/Microsoft.Extensions.Configuration.AzureAppConfiguration/AzureKeyVaultReference/CachedKeyVaultSecret.cs b/src/Microsoft.Extensions.Configuration.AzureAppConfiguration/AzureKeyVaultReference/CachedKeyVaultSecret.cs
index ab09311ed..661033fe9 100644
--- a/src/Microsoft.Extensions.Configuration.AzureAppConfiguration/AzureKeyVaultReference/CachedKeyVaultSecret.cs
+++ b/src/Microsoft.Extensions.Configuration.AzureAppConfiguration/AzureKeyVaultReference/CachedKeyVaultSecret.cs
@@ -10,7 +10,7 @@ internal class CachedKeyVaultSecret
         ///// <summary>
         ///// The value of the Key Vault secret.
         ///// </summary>
-        public string SecretValue { get; set; }
+        public string? SecretValue { get; set; }
 
         /// <summary>
         /// The time when this secret should be reloaded from Key Vault.
@@ -30,9 +30,9 @@ internal class CachedKeyVaultSecret
         /// <summary>
         /// The source <see cref="Uri"/> for this secret.
         /// </summary>
-        public Uri SourceId { get; }
+        public Uri? SourceId { get; }
 
-        public CachedKeyVaultSecret(string secretValue = null, Uri sourceId = null, DateTimeOffset? refreshAt = null, int refreshAttempts = 0)
+        public CachedKeyVaultSecret(string? secretValue = null, Uri? sourceId = null, DateTimeOffset? refreshAt = null, int refreshAttempts = 0)
         {
             SecretValue = secretValue;
             RefreshAt = refreshAt;
diff --git a/src/Microsoft.Extensions.Configuration.AzureAppConfiguration/ConfigurationClientManager.cs b/src/Microsoft.Extensions.Configuration.AzureAppConfiguration/ConfigurationClientManager.cs
index 61840d036..c652d4ee0 100644
--- a/src/Microsoft.Extensions.Configuration.AzureAppConfiguration/ConfigurationClientManager.cs
+++ b/src/Microsoft.Extensions.Configuration.AzureAppConfiguration/ConfigurationClientManager.cs
@@ -1,6 +1,7 @@
 // Copyright (c) Microsoft Corporation.
 // Licensed under the MIT license.
 //
+#nullable disable
 
 using Azure.Data.AppConfiguration;
 using DnsClient;
diff --git a/src/Microsoft.Extensions.Configuration.AzureAppConfiguration/EndpointComparer.cs b/src/Microsoft.Extensions.Configuration.AzureAppConfiguration/EndpointComparer.cs
index 362190ed9..42114695f 100644
--- a/src/Microsoft.Extensions.Configuration.AzureAppConfiguration/EndpointComparer.cs
+++ b/src/Microsoft.Extensions.Configuration.AzureAppConfiguration/EndpointComparer.cs
@@ -8,7 +8,7 @@ namespace Microsoft.Extensions.Configuration.AzureAppConfiguration
 {
     internal class EndpointComparer : IEqualityComparer<Uri>
     {
-        public bool Equals(Uri endpoint1, Uri endpoint2)
+        public bool Equals(Uri? endpoint1, Uri? endpoint2)
         {
             return Uri.Compare(endpoint1,
                                endpoint2,
diff --git a/src/Microsoft.Extensions.Configuration.AzureAppConfiguration/Exceptions/KeyVaultReferenceException.cs b/src/Microsoft.Extensions.Configuration.AzureAppConfiguration/Exceptions/KeyVaultReferenceException.cs
index 7d549a068..7a69a293a 100644
--- a/src/Microsoft.Extensions.Configuration.AzureAppConfiguration/Exceptions/KeyVaultReferenceException.cs
+++ b/src/Microsoft.Extensions.Configuration.AzureAppConfiguration/Exceptions/KeyVaultReferenceException.cs
@@ -34,26 +34,26 @@ public KeyVaultReferenceException(string message,
         /// <summary>
         /// The key of the Key Vault reference that caused the exception.
         /// </summary>
-        public string Key { get; set; }
+        public string? Key { get; set; }
 
         /// <summary>
         /// The label of the Key Vault reference that caused the exception.
         /// </summary>
-        public string Label { get; set; }
+        public string? Label { get; set; }
 
         /// <summary>
         /// The etag of the Key Vault reference that caused the exception.
         /// </summary>
-        public string Etag { get; set; }
+        public string? Etag { get; set; }
 
         /// <summary>
         /// The secret identifier used by the Azure Key Vault reference that caused the exception.
         /// </summary>
-        public string SecretIdentifier { get; set; }
+        public string? SecretIdentifier { get; set; }
 
         /// <summary>
         /// The error code, if available, describing the cause of the exception. 
         /// </summary>
-        public string ErrorCode { get; set; }
+        public string? ErrorCode { get; set; }
     }
 }
diff --git a/src/Microsoft.Extensions.Configuration.AzureAppConfiguration/Extensions/EventGridEventExtensions.cs b/src/Microsoft.Extensions.Configuration.AzureAppConfiguration/Extensions/EventGridEventExtensions.cs
index ee9043248..d9d53c376 100644
--- a/src/Microsoft.Extensions.Configuration.AzureAppConfiguration/Extensions/EventGridEventExtensions.cs
+++ b/src/Microsoft.Extensions.Configuration.AzureAppConfiguration/Extensions/EventGridEventExtensions.cs
@@ -20,7 +20,7 @@ public static class EventGridEventExtensions
         /// <param name="eventGridEvent"> EventGridEvent from EventGrid</param>
         /// <param name="pushNotification"> If this method returns true, the pushNotification  object contains details populated from eventGridEvent. If this method returns false, the pushNotification object is null. </param>
         /// <returns></returns>
-        public static bool TryCreatePushNotification(this EventGridEvent eventGridEvent, out PushNotification pushNotification)
+        public static bool TryCreatePushNotification(this EventGridEvent eventGridEvent, out PushNotification? pushNotification)
         {
             pushNotification = null;
 
@@ -29,9 +29,9 @@ public static bool TryCreatePushNotification(this EventGridEvent eventGridEvent,
                 return false;
             }
 
-            if (Uri.TryCreate(eventGridEvent.Subject, UriKind.Absolute, out Uri resourceUri))
+            if (Uri.TryCreate(eventGridEvent.Subject, UriKind.Absolute, out Uri? resourceUri))
             {
-                string syncToken = null;
+                string? syncToken = null;
 
                 try
                 {
diff --git a/src/Microsoft.Extensions.Configuration.AzureAppConfiguration/Extensions/StringExtensions.cs b/src/Microsoft.Extensions.Configuration.AzureAppConfiguration/Extensions/StringExtensions.cs
index 1bc69ae90..07c665504 100644
--- a/src/Microsoft.Extensions.Configuration.AzureAppConfiguration/Extensions/StringExtensions.cs
+++ b/src/Microsoft.Extensions.Configuration.AzureAppConfiguration/Extensions/StringExtensions.cs
@@ -8,7 +8,7 @@ namespace Microsoft.Extensions.Configuration.AzureAppConfiguration.Extensions
 {
     internal static class StringExtensions
     {
-        public static bool TryParseContentType(this string contentTypeString, out ContentType contentType)
+        public static bool TryParseContentType(this string contentTypeString, out ContentType? contentType)
         {
             contentType = null;
 
@@ -35,7 +35,7 @@ public static bool TryParseContentType(this string contentTypeString, out Conten
             }
         }
 
-        public static string NormalizeNull(this string s)
+        public static string? NormalizeNull(this string? s)
         {
             return s == LabelFilter.Null ? null : s;
         }
diff --git a/src/Microsoft.Extensions.Configuration.AzureAppConfiguration/FeatureManagement/ClientFilter.cs b/src/Microsoft.Extensions.Configuration.AzureAppConfiguration/FeatureManagement/ClientFilter.cs
index 12145cd70..64385431c 100644
--- a/src/Microsoft.Extensions.Configuration.AzureAppConfiguration/FeatureManagement/ClientFilter.cs
+++ b/src/Microsoft.Extensions.Configuration.AzureAppConfiguration/FeatureManagement/ClientFilter.cs
@@ -7,7 +7,7 @@ namespace Microsoft.Extensions.Configuration.AzureAppConfiguration.FeatureManage
 {
     internal class ClientFilter
     {
-        public string Name { get; set; }
+        public string Name { get; set; } = string.Empty;
 
         public JsonElement Parameters { get; set; }
     }
diff --git a/src/Microsoft.Extensions.Configuration.AzureAppConfiguration/FeatureManagement/FeatureAllocation.cs b/src/Microsoft.Extensions.Configuration.AzureAppConfiguration/FeatureManagement/FeatureAllocation.cs
index 0b2877e6e..258c24d33 100644
--- a/src/Microsoft.Extensions.Configuration.AzureAppConfiguration/FeatureManagement/FeatureAllocation.cs
+++ b/src/Microsoft.Extensions.Configuration.AzureAppConfiguration/FeatureManagement/FeatureAllocation.cs
@@ -7,16 +7,16 @@ namespace Microsoft.Extensions.Configuration.AzureAppConfiguration.FeatureManage
 {
     internal class FeatureAllocation
     {
-        public string DefaultWhenDisabled { get; set; }
+        public string? DefaultWhenDisabled { get; set; }
 
-        public string DefaultWhenEnabled { get; set; }
+        public string? DefaultWhenEnabled { get; set; }
 
-        public IEnumerable<FeatureUserAllocation> User { get; set; }
+        public IEnumerable<FeatureUserAllocation>? User { get; set; }
 
-        public IEnumerable<FeatureGroupAllocation> Group { get; set; }
+        public IEnumerable<FeatureGroupAllocation>? Group { get; set; }
 
-        public IEnumerable<FeaturePercentileAllocation> Percentile { get; set; }
+        public IEnumerable<FeaturePercentileAllocation>? Percentile { get; set; }
 
-        public string Seed { get; set; }
+        public string? Seed { get; set; }
     }
 }
diff --git a/src/Microsoft.Extensions.Configuration.AzureAppConfiguration/FeatureManagement/FeatureConditions.cs b/src/Microsoft.Extensions.Configuration.AzureAppConfiguration/FeatureManagement/FeatureConditions.cs
index d1c23003a..98a873f96 100644
--- a/src/Microsoft.Extensions.Configuration.AzureAppConfiguration/FeatureManagement/FeatureConditions.cs
+++ b/src/Microsoft.Extensions.Configuration.AzureAppConfiguration/FeatureManagement/FeatureConditions.cs
@@ -9,6 +9,6 @@ internal class FeatureConditions
     {
         public List<ClientFilter> ClientFilters { get; set; } = new List<ClientFilter>();
 
-        public string RequirementType { get; set; }
+        public string? RequirementType { get; set; }
     }
 }
diff --git a/src/Microsoft.Extensions.Configuration.AzureAppConfiguration/FeatureManagement/FeatureFlag.cs b/src/Microsoft.Extensions.Configuration.AzureAppConfiguration/FeatureManagement/FeatureFlag.cs
index 31af50a68..282de9e24 100644
--- a/src/Microsoft.Extensions.Configuration.AzureAppConfiguration/FeatureManagement/FeatureFlag.cs
+++ b/src/Microsoft.Extensions.Configuration.AzureAppConfiguration/FeatureManagement/FeatureFlag.cs
@@ -7,16 +7,16 @@ namespace Microsoft.Extensions.Configuration.AzureAppConfiguration.FeatureManage
 {
     internal class FeatureFlag
     {
-        public string Id { get; set; }
+        public string Id { get; set; } = string.Empty;
 
         public bool Enabled { get; set; }
 
-        public FeatureConditions Conditions { get; set; }
+        public FeatureConditions? Conditions { get; set; }
 
-        public IEnumerable<FeatureVariant> Variants { get; set; }
+        public IEnumerable<FeatureVariant>? Variants { get; set; }
 
-        public FeatureAllocation Allocation { get; set; }
+        public FeatureAllocation? Allocation { get; set; }
 
-        public FeatureTelemetry Telemetry { get; set; }
+        public FeatureTelemetry? Telemetry { get; set; }
     }
 }
diff --git a/src/Microsoft.Extensions.Configuration.AzureAppConfiguration/FeatureManagement/FeatureFlagOptions.cs b/src/Microsoft.Extensions.Configuration.AzureAppConfiguration/FeatureManagement/FeatureFlagOptions.cs
index 4b6d56d6d..66186a8dd 100644
--- a/src/Microsoft.Extensions.Configuration.AzureAppConfiguration/FeatureManagement/FeatureFlagOptions.cs
+++ b/src/Microsoft.Extensions.Configuration.AzureAppConfiguration/FeatureManagement/FeatureFlagOptions.cs
@@ -33,7 +33,7 @@ internal TimeSpan RefreshInterval
         /// <summary>
         /// The label that feature flags will be selected from.
         /// </summary>
-        public string Label { get; set; }
+        public string? Label { get; set; }
 
         /// <summary>
         /// The time after which the cached values of the feature flags expire.  Must be greater than or equal to 1 second.
@@ -81,7 +81,7 @@ public FeatureFlagOptions SetRefreshInterval(TimeSpan refreshInterval)
         /// The characters asterisk (*), comma (,) and backslash (\) are reserved and must be escaped using a backslash (\).
         /// Up to 5 tag filters can be provided. If no tag filters are provided, feature flags will not be filtered based on tags.
         /// </param>
-        public FeatureFlagOptions Select(string featureFlagFilter, string labelFilter = LabelFilter.Null, IEnumerable<string> tagFilters = null)
+        public FeatureFlagOptions Select(string featureFlagFilter, string labelFilter = LabelFilter.Null, IEnumerable<string>? tagFilters = null)
         {
             if (string.IsNullOrEmpty(featureFlagFilter))
             {
diff --git a/src/Microsoft.Extensions.Configuration.AzureAppConfiguration/FeatureManagement/FeatureGroupAllocation.cs b/src/Microsoft.Extensions.Configuration.AzureAppConfiguration/FeatureManagement/FeatureGroupAllocation.cs
index f39ca8cdc..eb11d7d6d 100644
--- a/src/Microsoft.Extensions.Configuration.AzureAppConfiguration/FeatureManagement/FeatureGroupAllocation.cs
+++ b/src/Microsoft.Extensions.Configuration.AzureAppConfiguration/FeatureManagement/FeatureGroupAllocation.cs
@@ -7,8 +7,8 @@ namespace Microsoft.Extensions.Configuration.AzureAppConfiguration.FeatureManage
 {
     internal class FeatureGroupAllocation
     {
-        public string Variant { get; set; }
+        public string? Variant { get; set; }
 
-        public IEnumerable<string> Groups { get; set; }
+        public IEnumerable<string>? Groups { get; set; }
     }
 }
diff --git a/src/Microsoft.Extensions.Configuration.AzureAppConfiguration/FeatureManagement/FeatureManagementKeyValueAdapter.cs b/src/Microsoft.Extensions.Configuration.AzureAppConfiguration/FeatureManagement/FeatureManagementKeyValueAdapter.cs
index fdd7f2fdf..a950525be 100644
--- a/src/Microsoft.Extensions.Configuration.AzureAppConfiguration/FeatureManagement/FeatureManagementKeyValueAdapter.cs
+++ b/src/Microsoft.Extensions.Configuration.AzureAppConfiguration/FeatureManagement/FeatureManagementKeyValueAdapter.cs
@@ -1,6 +1,7 @@
 // Copyright (c) Microsoft Corporation.
 // Licensed under the MIT license.
 //
+#nullable disable
 using Azure.Data.AppConfiguration;
 using Microsoft.Extensions.Configuration.AzureAppConfiguration.Extensions;
 using System;
diff --git a/src/Microsoft.Extensions.Configuration.AzureAppConfiguration/FeatureManagement/FeaturePercentileAllocation.cs b/src/Microsoft.Extensions.Configuration.AzureAppConfiguration/FeatureManagement/FeaturePercentileAllocation.cs
index 1d107dba7..af2a1b6f0 100644
--- a/src/Microsoft.Extensions.Configuration.AzureAppConfiguration/FeatureManagement/FeaturePercentileAllocation.cs
+++ b/src/Microsoft.Extensions.Configuration.AzureAppConfiguration/FeatureManagement/FeaturePercentileAllocation.cs
@@ -6,7 +6,7 @@ namespace Microsoft.Extensions.Configuration.AzureAppConfiguration.FeatureManage
 {
     internal class FeaturePercentileAllocation
     {
-        public string Variant { get; set; }
+        public string? Variant { get; set; }
 
         public double From { get; set; }
 
diff --git a/src/Microsoft.Extensions.Configuration.AzureAppConfiguration/FeatureManagement/FeatureTelemetry.cs b/src/Microsoft.Extensions.Configuration.AzureAppConfiguration/FeatureManagement/FeatureTelemetry.cs
index 09d8dd71e..1a28b6c5b 100644
--- a/src/Microsoft.Extensions.Configuration.AzureAppConfiguration/FeatureManagement/FeatureTelemetry.cs
+++ b/src/Microsoft.Extensions.Configuration.AzureAppConfiguration/FeatureManagement/FeatureTelemetry.cs
@@ -10,6 +10,6 @@ internal class FeatureTelemetry
     {
         public bool Enabled { get; set; }
 
-        public IDictionary<string, string> Metadata { get; set; }
+        public IDictionary<string, string>? Metadata { get; set; }
     }
 }
diff --git a/src/Microsoft.Extensions.Configuration.AzureAppConfiguration/FeatureManagement/FeatureUserAllocation.cs b/src/Microsoft.Extensions.Configuration.AzureAppConfiguration/FeatureManagement/FeatureUserAllocation.cs
index fc403d6e8..42c439218 100644
--- a/src/Microsoft.Extensions.Configuration.AzureAppConfiguration/FeatureManagement/FeatureUserAllocation.cs
+++ b/src/Microsoft.Extensions.Configuration.AzureAppConfiguration/FeatureManagement/FeatureUserAllocation.cs
@@ -7,8 +7,8 @@ namespace Microsoft.Extensions.Configuration.AzureAppConfiguration.FeatureManage
 {
     internal class FeatureUserAllocation
     {
-        public string Variant { get; set; }
+        public string? Variant { get; set; }
 
-        public IEnumerable<string> Users { get; set; }
+        public IEnumerable<string>? Users { get; set; }
     }
 }
diff --git a/src/Microsoft.Extensions.Configuration.AzureAppConfiguration/FeatureManagement/FeatureVariant.cs b/src/Microsoft.Extensions.Configuration.AzureAppConfiguration/FeatureManagement/FeatureVariant.cs
index 7bfd9d6f7..84c1d18c4 100644
--- a/src/Microsoft.Extensions.Configuration.AzureAppConfiguration/FeatureManagement/FeatureVariant.cs
+++ b/src/Microsoft.Extensions.Configuration.AzureAppConfiguration/FeatureManagement/FeatureVariant.cs
@@ -7,10 +7,10 @@ namespace Microsoft.Extensions.Configuration.AzureAppConfiguration.FeatureManage
 {
     internal class FeatureVariant
     {
-        public string Name { get; set; }
+        public string Name { get; set; } = string.Empty;
 
         public JsonElement ConfigurationValue { get; set; }
 
-        public string StatusOverride { get; set; }
+        public string? StatusOverride { get; set; }
     }
 }
diff --git a/src/Microsoft.Extensions.Configuration.AzureAppConfiguration/FeatureManagement/JsonFlattener.cs b/src/Microsoft.Extensions.Configuration.AzureAppConfiguration/FeatureManagement/JsonFlattener.cs
index fa5983c1c..70ee5ccd7 100644
--- a/src/Microsoft.Extensions.Configuration.AzureAppConfiguration/FeatureManagement/JsonFlattener.cs
+++ b/src/Microsoft.Extensions.Configuration.AzureAppConfiguration/FeatureManagement/JsonFlattener.cs
@@ -12,7 +12,7 @@ internal class JsonFlattener
     {
         private readonly List<KeyValuePair<string, string>> _data = new List<KeyValuePair<string, string>>();
         private readonly Stack<string> _context = new Stack<string>();
-        private string _currentPath;
+        private string _currentPath = string.Empty;
 
         public List<KeyValuePair<string, string>> FlattenJson(JsonElement rootElement)
         {
diff --git a/src/Microsoft.Extensions.Configuration.AzureAppConfiguration/IKeyValueAdapter.cs b/src/Microsoft.Extensions.Configuration.AzureAppConfiguration/IKeyValueAdapter.cs
index de13314e1..0204a0f6b 100644
--- a/src/Microsoft.Extensions.Configuration.AzureAppConfiguration/IKeyValueAdapter.cs
+++ b/src/Microsoft.Extensions.Configuration.AzureAppConfiguration/IKeyValueAdapter.cs
@@ -15,7 +15,7 @@ internal interface IKeyValueAdapter
 
         bool CanProcess(ConfigurationSetting setting);
 
-        void OnChangeDetected(ConfigurationSetting setting = null);
+        void OnChangeDetected(ConfigurationSetting? setting = null);
 
         void OnConfigUpdated();
 
diff --git a/src/Microsoft.Extensions.Configuration.AzureAppConfiguration/KeyValueChange.cs b/src/Microsoft.Extensions.Configuration.AzureAppConfiguration/KeyValueChange.cs
index 2286016d7..50a09b62a 100644
--- a/src/Microsoft.Extensions.Configuration.AzureAppConfiguration/KeyValueChange.cs
+++ b/src/Microsoft.Extensions.Configuration.AzureAppConfiguration/KeyValueChange.cs
@@ -18,10 +18,10 @@ internal struct KeyValueChange
 
         public string Key { get; set; }
 
-        public string Label { get; set; }
+        public string? Label { get; set; }
 
-        public ConfigurationSetting Current { get; set; }
+        public ConfigurationSetting? Current { get; set; }
 
-        public ConfigurationSetting Previous { get; set; }
+        public ConfigurationSetting? Previous { get; set; }
     }
 }
diff --git a/src/Microsoft.Extensions.Configuration.AzureAppConfiguration/Logger.cs b/src/Microsoft.Extensions.Configuration.AzureAppConfiguration/Logger.cs
index e68624086..e0f72e4a7 100644
--- a/src/Microsoft.Extensions.Configuration.AzureAppConfiguration/Logger.cs
+++ b/src/Microsoft.Extensions.Configuration.AzureAppConfiguration/Logger.cs
@@ -8,7 +8,7 @@ namespace Microsoft.Extensions.Configuration.AzureAppConfiguration
 {
     internal class Logger
     {
-        ILogger _logger;
+        ILogger? _logger;
 
         public Logger() { }
 
diff --git a/src/Microsoft.Extensions.Configuration.AzureAppConfiguration/Microsoft.Extensions.Configuration.AzureAppConfiguration.csproj b/src/Microsoft.Extensions.Configuration.AzureAppConfiguration/Microsoft.Extensions.Configuration.AzureAppConfiguration.csproj
index 8c8241a79..16dc39d73 100644
--- a/src/Microsoft.Extensions.Configuration.AzureAppConfiguration/Microsoft.Extensions.Configuration.AzureAppConfiguration.csproj
+++ b/src/Microsoft.Extensions.Configuration.AzureAppConfiguration/Microsoft.Extensions.Configuration.AzureAppConfiguration.csproj
@@ -5,6 +5,7 @@
   <PropertyGroup>
     <TargetFrameworks>netstandard2.0;netstandard2.1</TargetFrameworks>
     <LangVersion>8.0</LangVersion>
+    <Nullable>enable</Nullable>
     <Description>Microsoft.Extensions.Configuration.AzureAppConfiguration is a configuration provider for the .NET Core framework that allows developers to use Microsoft Azure App Configuration service as a configuration source in their applications.</Description>
     <SignAssembly>true</SignAssembly>
     <DelaySign>false</DelaySign>
diff --git a/src/Microsoft.Extensions.Configuration.AzureAppConfiguration/Models/KeyValueIdentifier.cs b/src/Microsoft.Extensions.Configuration.AzureAppConfiguration/Models/KeyValueIdentifier.cs
index 9a77346ac..c35b4cd03 100644
--- a/src/Microsoft.Extensions.Configuration.AzureAppConfiguration/Models/KeyValueIdentifier.cs
+++ b/src/Microsoft.Extensions.Configuration.AzureAppConfiguration/Models/KeyValueIdentifier.cs
@@ -15,15 +15,15 @@ internal struct KeyValueIdentifier
         /// <summary>
         /// Label of the key-value in App Configuration.
         /// </summary>
-        public string Label { get; set; }
+        public string? Label { get; set; }
 
-        public KeyValueIdentifier(string key, string label)
+        public KeyValueIdentifier(string key, string? label)
         {
             Key = key;
             Label = label.NormalizeNull();
         }
 
-        public override bool Equals(object obj)
+        public override bool Equals(object? obj)
         {
             if (obj is KeyValueIdentifier keyLabel)
             {
diff --git a/src/Microsoft.Extensions.Configuration.AzureAppConfiguration/Models/KeyValueSelector.cs b/src/Microsoft.Extensions.Configuration.AzureAppConfiguration/Models/KeyValueSelector.cs
index f01eb6559..e7049ef92 100644
--- a/src/Microsoft.Extensions.Configuration.AzureAppConfiguration/Models/KeyValueSelector.cs
+++ b/src/Microsoft.Extensions.Configuration.AzureAppConfiguration/Models/KeyValueSelector.cs
@@ -16,22 +16,22 @@ public class KeyValueSelector
         /// A filter that determines the set of keys that are included in the configuration provider.
         /// </summary>
         /// <remarks>See the documentation for this provider for details on the format of filter expressions</remarks>
-        public string KeyFilter { get; set; }
+        public string? KeyFilter { get; set; }
 
         /// <summary>
         /// A filter that determines what label to use when selecting key-values for the the configuration provider.
         /// </summary>
-        public string LabelFilter { get; set; }
+        public string? LabelFilter { get; set; }
 
         /// <summary>
         /// The name of the Azure App Configuration snapshot to use when selecting key-values for the configuration provider.
         /// </summary>
-        public string SnapshotName { get; set; }
+        public string? SnapshotName { get; set; }
 
         /// <summary>
         /// A filter that determines what tags to require when selecting key-values for the the configuration provider.
         /// </summary>
-        public IEnumerable<string> TagFilters { get; set; }
+        public IEnumerable<string>? TagFilters { get; set; }
 
         /// <summary>
         /// A boolean that signifies whether this selector is intended to select feature flags.
@@ -43,7 +43,7 @@ public class KeyValueSelector
         /// </summary>
         /// <param name="obj">The object to compare with the current object.</param>
         /// <returns>true if the specified object is equal to the current object; otherwise, false.</returns>
-        public override bool Equals(object obj)
+        public override bool Equals(object? obj)
         {
             if (obj is KeyValueSelector selector)
             {
diff --git a/src/Microsoft.Extensions.Configuration.AzureAppConfiguration/Models/KeyValueWatcher.cs b/src/Microsoft.Extensions.Configuration.AzureAppConfiguration/Models/KeyValueWatcher.cs
index a9f59e745..b785e18f1 100644
--- a/src/Microsoft.Extensions.Configuration.AzureAppConfiguration/Models/KeyValueWatcher.cs
+++ b/src/Microsoft.Extensions.Configuration.AzureAppConfiguration/Models/KeyValueWatcher.cs
@@ -12,17 +12,17 @@ internal class KeyValueWatcher
         /// <summary>
         /// Key of the key-value to be watched.
         /// </summary>
-        public string Key { get; set; }
+        public string Key { get; set; } = string.Empty;
 
         /// <summary>
         /// Label of the key-value to be watched.
         /// </summary>
-        public string Label { get; set; }
+        public string? Label { get; set; }
 
         /// <summary>
         /// Tags of the key-value to be watched.
         /// </summary>
-        public IEnumerable<string> Tags { get; set; }
+        public IEnumerable<string>? Tags { get; set; }
 
         /// <summary>
         /// A flag to refresh all key-values.
@@ -39,7 +39,7 @@ internal class KeyValueWatcher
         /// </summary>
         public DateTimeOffset NextRefreshTime { get; set; }
 
-        public override bool Equals(object obj)
+        public override bool Equals(object? obj)
         {
             if (obj is KeyValueWatcher kvWatcher)
             {
diff --git a/src/Microsoft.Extensions.Configuration.AzureAppConfiguration/PushNotification.cs b/src/Microsoft.Extensions.Configuration.AzureAppConfiguration/PushNotification.cs
index 1690645d3..837edc31f 100644
--- a/src/Microsoft.Extensions.Configuration.AzureAppConfiguration/PushNotification.cs
+++ b/src/Microsoft.Extensions.Configuration.AzureAppConfiguration/PushNotification.cs
@@ -13,16 +13,16 @@ public class PushNotification
         /// <summary>
         /// The URI of the resource which triggered the <see cref="PushNotification"/>.
         /// </summary>
-        public Uri ResourceUri { get; set; }
+        public Uri? ResourceUri { get; set; }
 
         /// <summary>
         /// The Synchronization Token to be added to the next request to the App Configuration Service.
         /// </summary>
-        public string SyncToken { get; set; }
+        public string? SyncToken { get; set; }
 
         /// <summary>
         /// The Type of Event which triggered the <see cref="PushNotification"/>.
         /// </summary>
-        public string EventType { get; set; }
+        public string? EventType { get; set; }
     }
 }
diff --git a/src/Microsoft.Extensions.Configuration.AzureAppConfiguration/RequestTracingOptions.cs b/src/Microsoft.Extensions.Configuration.AzureAppConfiguration/RequestTracingOptions.cs
index 2f50a3856..ee4b3a32c 100644
--- a/src/Microsoft.Extensions.Configuration.AzureAppConfiguration/RequestTracingOptions.cs
+++ b/src/Microsoft.Extensions.Configuration.AzureAppConfiguration/RequestTracingOptions.cs
@@ -44,17 +44,17 @@ internal class RequestTracingOptions
         /// <summary>
         /// Version of the Microsoft.FeatureManagement assembly, if present in the application.
         /// </summary>
-        public string FeatureManagementVersion { get; set; }
+        public string? FeatureManagementVersion { get; set; }
 
         /// <summary>
         /// Version of the Microsoft.FeatureManagement.AspNetCore assembly, if present in the application.
         /// </summary>
-        public string FeatureManagementAspNetCoreVersion { get; set; }
+        public string? FeatureManagementAspNetCoreVersion { get; set; }
 
         /// <summary>
         /// Version of the Aspire.Microsoft.Extensions.Configuration.AzureAppConfiguration assembly, if present in the application.
         /// </summary>
-        public string AspireComponentVersion { get; set; }
+        public string? AspireComponentVersion { get; set; }
 
         /// <summary>
         /// Flag to indicate whether Microsoft.AspNetCore.SignalR assembly is present in the application.
diff --git a/src/Microsoft.Extensions.Configuration.AzureAppConfiguration/SnapshotReference/SnapshotReference.cs b/src/Microsoft.Extensions.Configuration.AzureAppConfiguration/SnapshotReference/SnapshotReference.cs
index b0731f1c0..e8c1dd708 100644
--- a/src/Microsoft.Extensions.Configuration.AzureAppConfiguration/SnapshotReference/SnapshotReference.cs
+++ b/src/Microsoft.Extensions.Configuration.AzureAppConfiguration/SnapshotReference/SnapshotReference.cs
@@ -6,6 +6,6 @@ namespace Microsoft.Extensions.Configuration.AzureAppConfiguration.SnapshotRefer
 {
     internal class SnapshotReference
     {
-        public string SnapshotName { get; set; }
+        public string SnapshotName { get; set; } = string.Empty;
     }
 }
diff --git a/src/Microsoft.Extensions.Configuration.AzureAppConfiguration/TracingUtils.cs b/src/Microsoft.Extensions.Configuration.AzureAppConfiguration/TracingUtils.cs
index 33050b5b8..77e8ca610 100644
--- a/src/Microsoft.Extensions.Configuration.AzureAppConfiguration/TracingUtils.cs
+++ b/src/Microsoft.Extensions.Configuration.AzureAppConfiguration/TracingUtils.cs
@@ -1,6 +1,7 @@
 // Copyright (c) Microsoft Corporation.
 // Licensed under the MIT license.
 //
+#nullable disable
 using System;
 using System.Collections.Generic;
 using System.Diagnostics;