diff --git a/Microsoft.Azure.Cosmos.Encryption.Custom/src/AeadAes/AeAesEncryptionProcessor.cs b/Microsoft.Azure.Cosmos.Encryption.Custom/src/AeadAes/AeAesEncryptionProcessor.cs
index 0944714aac..c7eb3658d4 100644
--- a/Microsoft.Azure.Cosmos.Encryption.Custom/src/AeadAes/AeAesEncryptionProcessor.cs
+++ b/Microsoft.Azure.Cosmos.Encryption.Custom/src/AeadAes/AeAesEncryptionProcessor.cs
@@ -13,6 +13,8 @@ namespace Microsoft.Azure.Cosmos.Encryption.Custom
     using Newtonsoft.Json;
     using Newtonsoft.Json.Linq;
 
+#pragma warning disable IDE0057 // Use range operator
+#pragma warning disable VSTHRD103 // Call async methods when in an async method
     internal static class AeAesEncryptionProcessor
     {
         public static async Task<Stream> EncryptAsync(
@@ -65,6 +67,7 @@ public static async Task<Stream> EncryptAsync(
                     encryptionOptions.PathsToEncrypt);
 
             itemJObj.Add(Constants.EncryptedInfo, JObject.FromObject(encryptionProperties));
+
             input.Dispose();
             return EncryptionProcessor.BaseSerializer.ToStream(itemJObj);
         }
@@ -113,4 +116,7 @@ internal static async Task<DecryptionContext> DecryptContentAsync(
             return decryptionContext;
         }
     }
+
+#pragma warning restore IDE0057 // Use range operator
+#pragma warning restore VSTHRD103 // Call async methods when in an async method
 }
diff --git a/Microsoft.Azure.Cosmos.Encryption.Custom/src/AeadAes/AeadAes256CbcHmac256Algorithm.cs b/Microsoft.Azure.Cosmos.Encryption.Custom/src/AeadAes/AeadAes256CbcHmac256Algorithm.cs
index 6ea90a33bf..dc946861ae 100644
--- a/Microsoft.Azure.Cosmos.Encryption.Custom/src/AeadAes/AeadAes256CbcHmac256Algorithm.cs
+++ b/Microsoft.Azure.Cosmos.Encryption.Custom/src/AeadAes/AeadAes256CbcHmac256Algorithm.cs
@@ -10,6 +10,8 @@ namespace Microsoft.Azure.Cosmos.Encryption.Custom
     using System.IO;
     using System.Security.Cryptography;
 
+#pragma warning disable SYSLIB0021 // Type or member is obsolete
+
     /// <summary>
     /// This class implements authenticated encryption algorithm with associated data as described in
     /// http://tools.ietf.org/html/draft-mcgrew-aead-aes-cbc-hmac-sha2-05 - specifically this implements
@@ -483,4 +485,6 @@ private static int GetCipherTextLength(int inputSize)
             return ((inputSize / BlockSizeInBytes) + 1) * BlockSizeInBytes;
         }
     }
+
+#pragma warning restore SYSLIB0021 // Type or member is obsolete
 }
\ No newline at end of file
diff --git a/Microsoft.Azure.Cosmos.Encryption.Custom/src/Common/CosmosJsonDotNetSerializer.cs b/Microsoft.Azure.Cosmos.Encryption.Custom/src/Common/CosmosJsonDotNetSerializer.cs
index b00c004476..9ed8056360 100644
--- a/Microsoft.Azure.Cosmos.Encryption.Custom/src/Common/CosmosJsonDotNetSerializer.cs
+++ b/Microsoft.Azure.Cosmos.Encryption.Custom/src/Common/CosmosJsonDotNetSerializer.cs
@@ -40,10 +40,14 @@ internal CosmosJsonDotNetSerializer(JsonSerializerSettings jsonSerializerSetting
         /// <returns>The object representing the deserialized stream</returns>
         public T FromStream<T>(Stream stream)
         {
+#if NET8_0_OR_GREATER
+            ArgumentNullException.ThrowIfNull(stream);
+#else
             if (stream == null)
             {
                 throw new ArgumentNullException(nameof(stream));
             }
+#endif
 
             if (typeof(Stream).IsAssignableFrom(typeof(T)))
             {
diff --git a/Microsoft.Azure.Cosmos.Encryption.Custom/src/CosmosDataEncryptionKeyProvider.cs b/Microsoft.Azure.Cosmos.Encryption.Custom/src/CosmosDataEncryptionKeyProvider.cs
index cd2fe84fbc..c6f1ffb66c 100644
--- a/Microsoft.Azure.Cosmos.Encryption.Custom/src/CosmosDataEncryptionKeyProvider.cs
+++ b/Microsoft.Azure.Cosmos.Encryption.Custom/src/CosmosDataEncryptionKeyProvider.cs
@@ -148,10 +148,14 @@ public async Task InitializeAsync(
                 throw new InvalidOperationException($"{nameof(CosmosDataEncryptionKeyProvider)} has already been initialized.");
             }
 
+#if NET8_0_OR_GREATER
+            ArgumentNullException.ThrowIfNull(database);
+#else
             if (database == null)
             {
                 throw new ArgumentNullException(nameof(database));
             }
+#endif
 
             ContainerResponse containerResponse = await database.CreateContainerIfNotExistsAsync(
                 containerId,
diff --git a/Microsoft.Azure.Cosmos.Encryption.Custom/src/DataEncryptionKey.cs b/Microsoft.Azure.Cosmos.Encryption.Custom/src/DataEncryptionKey.cs
index b764debfd5..810227479e 100644
--- a/Microsoft.Azure.Cosmos.Encryption.Custom/src/DataEncryptionKey.cs
+++ b/Microsoft.Azure.Cosmos.Encryption.Custom/src/DataEncryptionKey.cs
@@ -102,10 +102,14 @@ public static DataEncryptionKey Create(
             byte[] rawKey,
             string encryptionAlgorithm)
         {
+#if NET8_0_OR_GREATER
+            ArgumentNullException.ThrowIfNull(rawKey);
+#else
             if (rawKey == null)
             {
                 throw new ArgumentNullException(nameof(rawKey));
             }
+#endif
 
 #pragma warning disable CS0618 // Type or member is obsolete
             if (!string.Equals(encryptionAlgorithm, CosmosEncryptionAlgorithm.AEAes256CbcHmacSha256Randomized))
diff --git a/Microsoft.Azure.Cosmos.Encryption.Custom/src/DataEncryptionKeyContainerCore.cs b/Microsoft.Azure.Cosmos.Encryption.Custom/src/DataEncryptionKeyContainerCore.cs
index 90cf907abc..1fcdd8c783 100644
--- a/Microsoft.Azure.Cosmos.Encryption.Custom/src/DataEncryptionKeyContainerCore.cs
+++ b/Microsoft.Azure.Cosmos.Encryption.Custom/src/DataEncryptionKeyContainerCore.cs
@@ -67,10 +67,14 @@ public override async Task<ItemResponse<DataEncryptionKeyProperties>> CreateData
                 throw new ArgumentException(string.Format("Unsupported Encryption Algorithm {0}", encryptionAlgorithm), nameof(encryptionAlgorithm));
             }
 
+#if NET8_0_OR_GREATER
+            ArgumentNullException.ThrowIfNull(encryptionKeyWrapMetadata);
+#else
             if (encryptionKeyWrapMetadata == null)
             {
                 throw new ArgumentNullException(nameof(encryptionKeyWrapMetadata));
             }
+#endif
 
             CosmosDiagnosticsContext diagnosticsContext = CosmosDiagnosticsContext.Create(requestOptions);
 
@@ -155,10 +159,14 @@ public override async Task<ItemResponse<DataEncryptionKeyProperties>> RewrapData
            ItemRequestOptions requestOptions = null,
            CancellationToken cancellationToken = default)
         {
+#if NET8_0_OR_GREATER
+            ArgumentNullException.ThrowIfNull(newWrapMetadata);
+#else
             if (newWrapMetadata == null)
             {
                 throw new ArgumentNullException(nameof(newWrapMetadata));
             }
+#endif
 
             CosmosDiagnosticsContext diagnosticsContext = CosmosDiagnosticsContext.Create(requestOptions);
 
diff --git a/Microsoft.Azure.Cosmos.Encryption.Custom/src/DataEncryptionKeyContainerInlineCore.cs b/Microsoft.Azure.Cosmos.Encryption.Custom/src/DataEncryptionKeyContainerInlineCore.cs
index d918d85d4a..bab5cadd62 100644
--- a/Microsoft.Azure.Cosmos.Encryption.Custom/src/DataEncryptionKeyContainerInlineCore.cs
+++ b/Microsoft.Azure.Cosmos.Encryption.Custom/src/DataEncryptionKeyContainerInlineCore.cs
@@ -78,10 +78,14 @@ public override Task<ItemResponse<DataEncryptionKeyProperties>> RewrapDataEncryp
                 throw new ArgumentNullException(nameof(id));
             }
 
+#if NET8_0_OR_GREATER
+            ArgumentNullException.ThrowIfNull(newWrapMetadata);
+#else
             if (newWrapMetadata == null)
             {
                 throw new ArgumentNullException(nameof(newWrapMetadata));
             }
+#endif
 
             return TaskHelper.RunInlineIfNeededAsync(() =>
                 this.dataEncryptionKeyContainerCore.RewrapDataEncryptionKeyAsync(id, newWrapMetadata, encryptionAlgorithm, requestOptions, cancellationToken));
diff --git a/Microsoft.Azure.Cosmos.Encryption.Custom/src/DataEncryptionKeyFeedIterator{T}.cs b/Microsoft.Azure.Cosmos.Encryption.Custom/src/DataEncryptionKeyFeedIterator{T}.cs
index 18e4246fdc..d01422c81b 100644
--- a/Microsoft.Azure.Cosmos.Encryption.Custom/src/DataEncryptionKeyFeedIterator{T}.cs
+++ b/Microsoft.Azure.Cosmos.Encryption.Custom/src/DataEncryptionKeyFeedIterator{T}.cs
@@ -13,7 +13,7 @@ namespace Microsoft.Azure.Cosmos.Encryption.Custom
 
     internal sealed class DataEncryptionKeyFeedIterator<T> : FeedIterator<T>
     {
-        private readonly FeedIterator feedIterator;
+        private readonly DataEncryptionKeyFeedIterator feedIterator;
         private readonly CosmosResponseFactory responseFactory;
 
         public DataEncryptionKeyFeedIterator(
@@ -57,7 +57,7 @@ public override async Task<FeedResponse<T>> ReadNextAsync(CancellationToken canc
 
                 if (responseMessage.IsSuccessStatusCode && responseMessage.Content != null)
                 {
-                    dataEncryptionKeyPropertiesList = this.ConvertResponseToDataEncryptionKeyPropertiesList(
+                    dataEncryptionKeyPropertiesList = DataEncryptionKeyFeedIterator<T>.ConvertResponseToDataEncryptionKeyPropertiesList(
                         responseMessage.Content);
 
                     return (responseMessage, dataEncryptionKeyPropertiesList);
@@ -67,7 +67,7 @@ public override async Task<FeedResponse<T>> ReadNextAsync(CancellationToken canc
             }
         }
 
-        private List<T> ConvertResponseToDataEncryptionKeyPropertiesList(
+        private static List<T> ConvertResponseToDataEncryptionKeyPropertiesList(
             Stream content)
         {
             JObject contentJObj = EncryptionProcessor.BaseSerializer.FromStream<JObject>(content);
diff --git a/Microsoft.Azure.Cosmos.Encryption.Custom/src/DecryptableFeedResponse.cs b/Microsoft.Azure.Cosmos.Encryption.Custom/src/DecryptableFeedResponse.cs
index c16497ac20..24c07c71e4 100644
--- a/Microsoft.Azure.Cosmos.Encryption.Custom/src/DecryptableFeedResponse.cs
+++ b/Microsoft.Azure.Cosmos.Encryption.Custom/src/DecryptableFeedResponse.cs
@@ -45,10 +45,14 @@ internal static DecryptableFeedResponse<T> CreateResponse(
             ResponseMessage responseMessage,
             IReadOnlyCollection<T> resource)
         {
+#if NET8_0_OR_GREATER
+            ArgumentNullException.ThrowIfNull(responseMessage);
+#else
             if (responseMessage == null)
             {
                 throw new ArgumentNullException(nameof(responseMessage));
             }
+#endif
 
             using (responseMessage)
             {
diff --git a/Microsoft.Azure.Cosmos.Encryption.Custom/src/EncryptionContainer.cs b/Microsoft.Azure.Cosmos.Encryption.Custom/src/EncryptionContainer.cs
index a5ad419a52..f769e1504a 100644
--- a/Microsoft.Azure.Cosmos.Encryption.Custom/src/EncryptionContainer.cs
+++ b/Microsoft.Azure.Cosmos.Encryption.Custom/src/EncryptionContainer.cs
@@ -122,10 +122,14 @@ public override async Task<ResponseMessage> CreateItemStreamAsync(
             ItemRequestOptions requestOptions = null,
             CancellationToken cancellationToken = default)
         {
+#if NET8_0_OR_GREATER
+            ArgumentNullException.ThrowIfNull(streamPayload);
+#else
             if (streamPayload == null)
             {
                 throw new ArgumentNullException(nameof(streamPayload));
             }
+#endif
 
             CosmosDiagnosticsContext diagnosticsContext = CosmosDiagnosticsContext.Create(requestOptions);
             using (diagnosticsContext.CreateScope("CreateItemStream"))
@@ -304,6 +308,10 @@ public override async Task<ItemResponse<T>> ReplaceItemAsync<T>(
             ItemRequestOptions requestOptions = null,
             CancellationToken cancellationToken = default)
         {
+#if NET8_0_OR_GREATER
+            ArgumentNullException.ThrowIfNull(id);
+            ArgumentNullException.ThrowIfNull(item);
+#else
             if (id == null)
             {
                 throw new ArgumentNullException(nameof(id));
@@ -313,6 +321,7 @@ public override async Task<ItemResponse<T>> ReplaceItemAsync<T>(
             {
                 throw new ArgumentNullException(nameof(item));
             }
+#endif
 
             if (requestOptions is not EncryptionItemRequestOptions encryptionItemRequestOptions ||
                 encryptionItemRequestOptions.EncryptionOptions == null)
@@ -384,6 +393,10 @@ public override async Task<ResponseMessage> ReplaceItemStreamAsync(
             ItemRequestOptions requestOptions = null,
             CancellationToken cancellationToken = default)
         {
+#if NET8_0_OR_GREATER
+            ArgumentNullException.ThrowIfNull(id);
+            ArgumentNullException.ThrowIfNull(streamPayload);
+#else
             if (id == null)
             {
                 throw new ArgumentNullException(nameof(id));
@@ -393,6 +406,7 @@ public override async Task<ResponseMessage> ReplaceItemStreamAsync(
             {
                 throw new ArgumentNullException(nameof(streamPayload));
             }
+#endif
 
             CosmosDiagnosticsContext diagnosticsContext = CosmosDiagnosticsContext.Create(requestOptions);
             using (diagnosticsContext.CreateScope("ReplaceItemStream"))
@@ -428,11 +442,6 @@ private async Task<ResponseMessage> ReplaceItemHelperAsync(
                     cancellationToken);
             }
 
-            if (partitionKey == null)
-            {
-                throw new NotSupportedException($"{nameof(partitionKey)} cannot be null for operations using {nameof(EncryptionContainer)}.");
-            }
-
             streamPayload = await EncryptionProcessor.EncryptAsync(
                 streamPayload,
                 this.Encryptor,
@@ -536,10 +545,14 @@ public override async Task<ResponseMessage> UpsertItemStreamAsync(
             ItemRequestOptions requestOptions = null,
             CancellationToken cancellationToken = default)
         {
+#if NET8_0_OR_GREATER
+            ArgumentNullException.ThrowIfNull(streamPayload);
+#else
             if (streamPayload == null)
             {
                 throw new ArgumentNullException(nameof(streamPayload));
             }
+#endif
 
             CosmosDiagnosticsContext diagnosticsContext = CosmosDiagnosticsContext.Create(requestOptions);
             using (diagnosticsContext.CreateScope("UpsertItemStream"))
@@ -572,11 +585,6 @@ private async Task<ResponseMessage> UpsertItemHelperAsync(
                     cancellationToken);
             }
 
-            if (partitionKey == null)
-            {
-                throw new NotSupportedException($"{nameof(partitionKey)} cannot be null for operations using {nameof(EncryptionContainer)}.");
-            }
-
             streamPayload = await EncryptionProcessor.EncryptAsync(
                 streamPayload,
                 this.Encryptor,
diff --git a/Microsoft.Azure.Cosmos.Encryption.Custom/src/EncryptionExceptionFactory.cs b/Microsoft.Azure.Cosmos.Encryption.Custom/src/EncryptionExceptionFactory.cs
index 55884f1093..3b50114cdb 100644
--- a/Microsoft.Azure.Cosmos.Encryption.Custom/src/EncryptionExceptionFactory.cs
+++ b/Microsoft.Azure.Cosmos.Encryption.Custom/src/EncryptionExceptionFactory.cs
@@ -8,6 +8,7 @@ namespace Microsoft.Azure.Cosmos.Encryption.Custom
 
     internal static class EncryptionExceptionFactory
     {
+#pragma warning disable CA2208 // Instantiate argument exceptions correctly
         internal static ArgumentException InvalidKeySize(string algorithmName, int actualKeylength, int expectedLength)
         {
             return new ArgumentException(
@@ -28,6 +29,7 @@ internal static ArgumentException InvalidAlgorithmVersion(byte actual, byte expe
                 $"Invalid encryption algorithm version; actual: {actual:X2}, expected: {expected:X2}.",
                 "cipherText");
         }
+#pragma warning restore CA2208 // Instantiate argument exceptions correctly
 
         internal static ArgumentException InvalidAuthenticationTag()
         {
diff --git a/Microsoft.Azure.Cosmos.Encryption.Custom/src/EncryptionFeedIterator{T}.cs b/Microsoft.Azure.Cosmos.Encryption.Custom/src/EncryptionFeedIterator{T}.cs
index ee22f330ac..81f1516e1b 100644
--- a/Microsoft.Azure.Cosmos.Encryption.Custom/src/EncryptionFeedIterator{T}.cs
+++ b/Microsoft.Azure.Cosmos.Encryption.Custom/src/EncryptionFeedIterator{T}.cs
@@ -11,7 +11,7 @@ namespace Microsoft.Azure.Cosmos.Encryption.Custom
 
     internal sealed class EncryptionFeedIterator<T> : FeedIterator<T>
     {
-        private readonly FeedIterator feedIterator;
+        private readonly EncryptionFeedIterator feedIterator;
         private readonly CosmosResponseFactory responseFactory;
 
         public EncryptionFeedIterator(
@@ -31,8 +31,7 @@ public override async Task<FeedResponse<T>> ReadNextAsync(CancellationToken canc
             if (typeof(T) == typeof(DecryptableItem))
             {
                 IReadOnlyCollection<T> resource;
-                EncryptionFeedIterator encryptionFeedIterator = this.feedIterator as EncryptionFeedIterator;
-                (responseMessage, resource) = await encryptionFeedIterator.ReadNextWithoutDecryptionAsync<T>(cancellationToken);
+                (responseMessage, resource) = await this.feedIterator.ReadNextWithoutDecryptionAsync<T>(cancellationToken);
 
                 return DecryptableFeedResponse<T>.CreateResponse(
                     responseMessage,
diff --git a/Microsoft.Azure.Cosmos.Encryption.Custom/src/EncryptionKeyWrapMetadata.cs b/Microsoft.Azure.Cosmos.Encryption.Custom/src/EncryptionKeyWrapMetadata.cs
index e3c285531d..5855a011cf 100644
--- a/Microsoft.Azure.Cosmos.Encryption.Custom/src/EncryptionKeyWrapMetadata.cs
+++ b/Microsoft.Azure.Cosmos.Encryption.Custom/src/EncryptionKeyWrapMetadata.cs
@@ -114,18 +114,5 @@ public bool Equals(EncryptionKeyWrapMetadata other)
                    this.Value == other.Value &&
                    this.Name == other.Name;
         }
-
-        internal string GetName(EncryptionKeyWrapMetadata encryptionKeyWrapMetadata)
-        {
-            /* A legacy DEK may not have a Name value in meta-data*/
-            if (string.IsNullOrWhiteSpace(encryptionKeyWrapMetadata.Name))
-            {
-                return encryptionKeyWrapMetadata.Value;
-            }
-            else
-            {
-                return encryptionKeyWrapMetadata.Name;
-            }
-        }
     }
 }
\ No newline at end of file
diff --git a/Microsoft.Azure.Cosmos.Encryption.Custom/src/EncryptionProcessor.cs b/Microsoft.Azure.Cosmos.Encryption.Custom/src/EncryptionProcessor.cs
index e1e384d156..53d74390f8 100644
--- a/Microsoft.Azure.Cosmos.Encryption.Custom/src/EncryptionProcessor.cs
+++ b/Microsoft.Azure.Cosmos.Encryption.Custom/src/EncryptionProcessor.cs
@@ -112,7 +112,11 @@ public static async Task<Stream> EncryptAsync(
             }
 
             DecryptionContext decryptionContext = await DecryptInternalAsync(encryptor, diagnosticsContext, itemJObj, encryptionPropertiesJObj, cancellationToken);
+#if NET8_0_OR_GREATER
+            await input.DisposeAsync();
+#else
             input.Dispose();
+#endif
             return (BaseSerializer.ToStream(itemJObj), decryptionContext);
         }
 
@@ -181,6 +185,11 @@ private static void ValidateInputForEncrypt(
             Encryptor encryptor,
             EncryptionOptions encryptionOptions)
         {
+#if NET8_0_OR_GREATER
+            ArgumentNullException.ThrowIfNull(input);
+            ArgumentNullException.ThrowIfNull(encryptor);
+            ArgumentNullException.ThrowIfNull(encryptionOptions);
+#else
             if (input == null)
             {
                 throw new ArgumentNullException(nameof(input));
@@ -195,7 +204,9 @@ private static void ValidateInputForEncrypt(
             {
                 throw new ArgumentNullException(nameof(encryptionOptions));
             }
+#endif
 
+#pragma warning disable CA2208 // Instantiate argument exceptions correctly
             if (string.IsNullOrWhiteSpace(encryptionOptions.DataEncryptionKeyId))
             {
                 throw new ArgumentNullException(nameof(encryptionOptions.DataEncryptionKeyId));
@@ -210,6 +221,7 @@ private static void ValidateInputForEncrypt(
             {
                 throw new ArgumentNullException(nameof(encryptionOptions.PathsToEncrypt));
             }
+#pragma warning restore CA2208 // Instantiate argument exceptions correctly
         }
 
         private static JObject RetrieveItem(
diff --git a/Microsoft.Azure.Cosmos.Encryption.Custom/src/MdeServices/MdeEncryptionAlgorithm.cs b/Microsoft.Azure.Cosmos.Encryption.Custom/src/MdeServices/MdeEncryptionAlgorithm.cs
index 8bb3a09ed3..b35422d261 100644
--- a/Microsoft.Azure.Cosmos.Encryption.Custom/src/MdeServices/MdeEncryptionAlgorithm.cs
+++ b/Microsoft.Azure.Cosmos.Encryption.Custom/src/MdeServices/MdeEncryptionAlgorithm.cs
@@ -34,6 +34,10 @@ public MdeEncryptionAlgorithm(
             TimeSpan? cacheTimeToLive,
             bool withRawKey = false)
         {
+#if NET8_0_OR_GREATER
+            ArgumentNullException.ThrowIfNull(dekProperties);
+            ArgumentNullException.ThrowIfNull(encryptionKeyStoreProvider);
+#else
             if (dekProperties == null)
             {
                 throw new ArgumentNullException(nameof(dekProperties));
@@ -43,6 +47,7 @@ public MdeEncryptionAlgorithm(
             {
                 throw new ArgumentNullException(nameof(encryptionKeyStoreProvider));
             }
+#endif
 
             KeyEncryptionKey keyEncryptionKey = KeyEncryptionKey.GetOrCreate(
                 dekProperties.EncryptionKeyWrapMetadata.Name,
diff --git a/Microsoft.Azure.Cosmos.Encryption.Custom/src/MdeServices/MdeKeyWrapProvider.cs b/Microsoft.Azure.Cosmos.Encryption.Custom/src/MdeServices/MdeKeyWrapProvider.cs
index 6520ecd67e..297a4dac7e 100644
--- a/Microsoft.Azure.Cosmos.Encryption.Custom/src/MdeServices/MdeKeyWrapProvider.cs
+++ b/Microsoft.Azure.Cosmos.Encryption.Custom/src/MdeServices/MdeKeyWrapProvider.cs
@@ -28,10 +28,14 @@ public override Task<EncryptionKeyUnwrapResult> UnwrapKeyAsync(
             EncryptionKeyWrapMetadata metadata,
             CancellationToken cancellationToken)
         {
+#if NET8_0_OR_GREATER
+            ArgumentNullException.ThrowIfNull(metadata);
+#else
             if (metadata == null)
             {
                 throw new ArgumentNullException(nameof(metadata));
             }
+#endif
 
             KeyEncryptionKey keyEncryptionKey = KeyEncryptionKey.GetOrCreate(
                 metadata.Name,
@@ -47,10 +51,14 @@ public override Task<EncryptionKeyWrapResult> WrapKeyAsync(
             EncryptionKeyWrapMetadata metadata,
             CancellationToken cancellationToken)
         {
+#if NET8_0_OR_GREATER
+            ArgumentNullException.ThrowIfNull(metadata);
+#else
             if (metadata == null)
             {
                 throw new ArgumentNullException(nameof(metadata));
             }
+#endif
 
             KeyEncryptionKey keyEncryptionKey = KeyEncryptionKey.GetOrCreate(
                 metadata.Name,
diff --git a/Microsoft.Azure.Cosmos.Encryption.Custom/src/Microsoft.Azure.Cosmos.Encryption.Custom.csproj b/Microsoft.Azure.Cosmos.Encryption.Custom/src/Microsoft.Azure.Cosmos.Encryption.Custom.csproj
index ea968c3020..6f492824b6 100644
--- a/Microsoft.Azure.Cosmos.Encryption.Custom/src/Microsoft.Azure.Cosmos.Encryption.Custom.csproj
+++ b/Microsoft.Azure.Cosmos.Encryption.Custom/src/Microsoft.Azure.Cosmos.Encryption.Custom.csproj
@@ -1,6 +1,6 @@
 <Project Sdk="Microsoft.NET.Sdk">
   <PropertyGroup>
-    <TargetFramework>netstandard2.0</TargetFramework>
+    <TargetFrameworks>netstandard2.0;net8.0</TargetFrameworks>
     <AssemblyName>Microsoft.Azure.Cosmos.Encryption.Custom</AssemblyName>
     <RootNamespace>Microsoft.Azure.Cosmos.Encryption.Custom</RootNamespace>
     <LangVersion>$(LangVersion)</LangVersion>
diff --git a/Microsoft.Azure.Cosmos.Encryption.Custom/src/SecurityUtility.cs b/Microsoft.Azure.Cosmos.Encryption.Custom/src/SecurityUtility.cs
index 632f1904d5..9a7ad82bbe 100644
--- a/Microsoft.Azure.Cosmos.Encryption.Custom/src/SecurityUtility.cs
+++ b/Microsoft.Azure.Cosmos.Encryption.Custom/src/SecurityUtility.cs
@@ -42,7 +42,9 @@ internal static string GetSHA256Hash(byte[] input)
 
             using (SHA256 sha256 = SHA256.Create())
             {
+#pragma warning disable CA1850 // Prefer static 'HashData' method over 'ComputeHash'
                 byte[] hashValue = sha256.ComputeHash(input);
+#pragma warning restore CA1850 // Prefer static 'HashData' method over 'ComputeHash'
                 return GetHexString(hashValue);
             }
         }
@@ -54,8 +56,12 @@ internal static string GetSHA256Hash(byte[] input)
         internal static void GenerateRandomBytes(byte[] randomBytes)
         {
             // Generate random bytes cryptographically.
+#if NET8_0_OR_GREATER
+            RandomNumberGenerator.Fill(randomBytes);
+#else
             using RNGCryptoServiceProvider rngCsp = new ();
             rngCsp.GetBytes(randomBytes);
+#endif
         }
 
         /// <summary>
diff --git a/Microsoft.Azure.Cosmos.Encryption.Custom/src/Transformation/JObjectSqlSerializer.Stable.cs b/Microsoft.Azure.Cosmos.Encryption.Custom/src/Transformation/JObjectSqlSerializer.Stable.cs
index f5b30910ab..12c8822b48 100644
--- a/Microsoft.Azure.Cosmos.Encryption.Custom/src/Transformation/JObjectSqlSerializer.Stable.cs
+++ b/Microsoft.Azure.Cosmos.Encryption.Custom/src/Transformation/JObjectSqlSerializer.Stable.cs
@@ -21,7 +21,7 @@ internal class JObjectSqlSerializer
 
         private static readonly JsonSerializerSettings JsonSerializerSettings = EncryptionProcessor.JsonSerializerSettings;
 
-        internal (TypeMarker, byte[]) Serialize(JToken propertyValue)
+        internal virtual (TypeMarker, byte[]) Serialize(JToken propertyValue)
         {
             switch (propertyValue.Type)
             {
diff --git a/Microsoft.Azure.Cosmos.Encryption.Custom/src/Transformation/MdeEncryptionProcessor.Preview.cs b/Microsoft.Azure.Cosmos.Encryption.Custom/src/Transformation/MdeEncryptionProcessor.Preview.cs
index 5f14d006bf..e4447c3c5c 100644
--- a/Microsoft.Azure.Cosmos.Encryption.Custom/src/Transformation/MdeEncryptionProcessor.Preview.cs
+++ b/Microsoft.Azure.Cosmos.Encryption.Custom/src/Transformation/MdeEncryptionProcessor.Preview.cs
@@ -36,7 +36,11 @@ public async Task<Stream> EncryptAsync(
 
             foreach (string pathToEncrypt in encryptionOptions.PathsToEncrypt)
             {
+#if NET8_0_OR_GREATER
+                string propertyName = pathToEncrypt[1..];
+#else
                 string propertyName = pathToEncrypt.Substring(1);
+#endif
                 if (!itemJObj.TryGetValue(propertyName, out JToken propertyValue))
                 {
                     continue;
@@ -69,7 +73,11 @@ public async Task<Stream> EncryptAsync(
                 pathsEncrypted);
 
             itemJObj.Add(Constants.EncryptedInfo, JObject.FromObject(encryptionProperties));
+#if NET8_0_OR_GREATER
+            await input.DisposeAsync();
+#else
             input.Dispose();
+#endif
             return EncryptionProcessor.BaseSerializer.ToStream(itemJObj);
         }
 
@@ -95,7 +103,12 @@ internal async Task<DecryptionContext> DecryptObjectAsync(
             List<string> pathsDecrypted = new (encryptionProperties.EncryptedPaths.Count());
             foreach (string path in encryptionProperties.EncryptedPaths)
             {
+#if NET8_0_OR_GREATER
+                string propertyName = path[1..];
+#else
                 string propertyName = path.Substring(1);
+#endif
+
                 if (!document.TryGetValue(propertyName, out JToken propertyValue))
                 {
                     // malformed document, such record shouldn't be there at all
diff --git a/Microsoft.Azure.Cosmos.Encryption.Custom/src/Transformation/MdeEncryptionProcessor.Stable.cs b/Microsoft.Azure.Cosmos.Encryption.Custom/src/Transformation/MdeEncryptionProcessor.Stable.cs
index ab05b4f770..1f9b628617 100644
--- a/Microsoft.Azure.Cosmos.Encryption.Custom/src/Transformation/MdeEncryptionProcessor.Stable.cs
+++ b/Microsoft.Azure.Cosmos.Encryption.Custom/src/Transformation/MdeEncryptionProcessor.Stable.cs
@@ -36,7 +36,11 @@ public async Task<Stream> EncryptAsync(
 
             foreach (string pathToEncrypt in encryptionOptions.PathsToEncrypt)
             {
+#if NET8_0_OR_GREATER
+                string propertyName = pathToEncrypt[1..];
+#else
                 string propertyName = pathToEncrypt.Substring(1);
+#endif
                 if (!itemJObj.TryGetValue(propertyName, out JToken propertyValue))
                 {
                     continue;
@@ -69,7 +73,11 @@ public async Task<Stream> EncryptAsync(
                 pathsEncrypted);
 
             itemJObj.Add(Constants.EncryptedInfo, JObject.FromObject(encryptionProperties));
+#if NET8_0_OR_GREATER
+            await input.DisposeAsync();
+#else
             input.Dispose();
+#endif
             return EncryptionProcessor.BaseSerializer.ToStream(itemJObj);
         }
 
@@ -94,7 +102,11 @@ internal async Task<DecryptionContext> DecryptObjectAsync(
             List<string> pathsDecrypted = new (encryptionProperties.EncryptedPaths.Count());
             foreach (string path in encryptionProperties.EncryptedPaths)
             {
+#if NET8_0_OR_GREATER
+                string propertyName = path[1..];
+#else
                 string propertyName = path.Substring(1);
+#endif
                 if (!document.TryGetValue(propertyName, out JToken propertyValue))
                 {
                     // malformed document, such record shouldn't be there at all
diff --git a/Microsoft.Azure.Cosmos.Encryption.Custom/src/Transformation/MemoryTextReader.cs b/Microsoft.Azure.Cosmos.Encryption.Custom/src/Transformation/MemoryTextReader.cs
index 71aed0fd14..c3f96c274a 100644
--- a/Microsoft.Azure.Cosmos.Encryption.Custom/src/Transformation/MemoryTextReader.cs
+++ b/Microsoft.Azure.Cosmos.Encryption.Custom/src/Transformation/MemoryTextReader.cs
@@ -71,6 +71,12 @@ public override int Read()
 
         public override int Read(char[] buffer, int index, int count)
         {
+#if NET8_0_OR_GREATER
+            ArgumentNullException.ThrowIfNull(buffer);
+            ArgumentOutOfRangeException.ThrowIfNegative(index);
+            ArgumentOutOfRangeException.ThrowIfNegative(count);
+            ArgumentOutOfRangeException.ThrowIfGreaterThan(count, buffer.Length - index);
+#else
             if (buffer == null)
             {
                 throw new ArgumentNullException(nameof(buffer));
@@ -90,6 +96,7 @@ public override int Read(char[] buffer, int index, int count)
             {
                 throw new ArgumentOutOfRangeException();
             }
+#endif
 
             if (this.closed)
             {
@@ -119,7 +126,11 @@ public override string ReadToEnd()
             }
 
             this.pos = this.length;
+#if NET8_0_OR_GREATER
+            return new string(this.chars[this.pos..this.length].Span);
+#else
             return new string(this.chars.Slice(this.pos, this.length - this.pos).ToArray());
+#endif
         }
 
         public override string ReadLine()
@@ -135,7 +146,11 @@ public override string ReadLine()
                 char ch = this.chars.Span[i];
                 if (ch == '\r' || ch == '\n')
                 {
+#if NET8_0_OR_GREATER
+                    string result = new (this.chars[this.pos..i].Span);
+#else
                     string result = new (this.chars.Slice(this.pos, i - this.pos).ToArray());
+#endif
                     this.pos = i + 1;
                     if (ch == '\r' && this.pos < this.length && this.chars.Span[this.pos] == '\n')
                     {
@@ -150,7 +165,11 @@ public override string ReadLine()
 
             if (i > this.pos)
             {
+#if NET8_0_OR_GREATER
+                string result = new (this.chars[this.pos..i].Span);
+#else
                 string result = new (this.chars.Slice(this.pos, i - this.pos).ToArray());
+#endif
                 this.pos = i;
                 return result;
             }
diff --git a/Microsoft.Azure.Cosmos.Encryption.Custom/tests/EmulatorTests/LegacyEncryptionTests.cs b/Microsoft.Azure.Cosmos.Encryption.Custom/tests/EmulatorTests/LegacyEncryptionTests.cs
index 30f6364a32..9ee43b8b07 100644
--- a/Microsoft.Azure.Cosmos.Encryption.Custom/tests/EmulatorTests/LegacyEncryptionTests.cs
+++ b/Microsoft.Azure.Cosmos.Encryption.Custom/tests/EmulatorTests/LegacyEncryptionTests.cs
@@ -1491,7 +1491,7 @@ private static EncryptionItemRequestOptions GetRequestOptions(
             };
         }
 
-        private static TransactionalBatchItemRequestOptions GetBatchItemRequestOptions(
+        private static EncryptionTransactionalBatchItemRequestOptions GetBatchItemRequestOptions(
             string dekId,
             List<string> pathsToEncrypt,
             string ifMatchEtag = null)
@@ -1812,13 +1812,11 @@ public override Stream ToStream<T>(T input)
                 MemoryStream streamPayload = new();
                 using (StreamWriter streamWriter = new(streamPayload, encoding: Encoding.UTF8, bufferSize: 1024, leaveOpen: true))
                 {
-                    using (JsonWriter writer = new JsonTextWriter(streamWriter))
-                    {
-                        writer.Formatting = Formatting.None;
-                        this.serializer.Serialize(writer, input);
-                        writer.Flush();
-                        streamWriter.Flush();
-                    }
+                    using JsonTextWriter writer = new (streamWriter);
+                    writer.Formatting = Formatting.None;
+                    this.serializer.Serialize(writer, input);
+                    writer.Flush();
+                    streamWriter.Flush();
                 }
 
                 streamPayload.Position = 0;
diff --git a/Microsoft.Azure.Cosmos.Encryption.Custom/tests/EmulatorTests/MdeCustomEncryptionTests.cs b/Microsoft.Azure.Cosmos.Encryption.Custom/tests/EmulatorTests/MdeCustomEncryptionTests.cs
index 661b876907..14b1915abb 100644
--- a/Microsoft.Azure.Cosmos.Encryption.Custom/tests/EmulatorTests/MdeCustomEncryptionTests.cs
+++ b/Microsoft.Azure.Cosmos.Encryption.Custom/tests/EmulatorTests/MdeCustomEncryptionTests.cs
@@ -1822,7 +1822,7 @@ private static EncryptionItemRequestOptions GetRequestOptions(
             }
         }
 
-        private static TransactionalBatchItemRequestOptions GetBatchItemRequestOptions(
+        private static EncryptionTransactionalBatchItemRequestOptions GetBatchItemRequestOptions(
             string dekId,
             List<string> pathsToEncrypt,
             string ifMatchEtag = null)
diff --git a/Microsoft.Azure.Cosmos.Encryption.Custom/tests/EmulatorTests/Microsoft.Azure.Cosmos.Encryption.Custom.EmulatorTests.csproj b/Microsoft.Azure.Cosmos.Encryption.Custom/tests/EmulatorTests/Microsoft.Azure.Cosmos.Encryption.Custom.EmulatorTests.csproj
index c5dfa8db0c..915be6c3f8 100644
--- a/Microsoft.Azure.Cosmos.Encryption.Custom/tests/EmulatorTests/Microsoft.Azure.Cosmos.Encryption.Custom.EmulatorTests.csproj
+++ b/Microsoft.Azure.Cosmos.Encryption.Custom/tests/EmulatorTests/Microsoft.Azure.Cosmos.Encryption.Custom.EmulatorTests.csproj
@@ -3,7 +3,7 @@
     <IsTestProject>true</IsTestProject>
     <TreatWarningsAsErrors>true</TreatWarningsAsErrors>
     <Platform>AnyCPU</Platform>
-    <TargetFramework>net6.0</TargetFramework>
+    <TargetFrameworks>net6.0;net8.0</TargetFrameworks>
     <IsPackable>false</IsPackable>
     <GenerateAssemblyInfo>false</GenerateAssemblyInfo>
     <RootNamespace>Microsoft.Azure.Cosmos.Encryption.Custom.EmulatorTests</RootNamespace>
diff --git a/Microsoft.Azure.Cosmos.Encryption.Custom/tests/Microsoft.Azure.Cosmos.Encryption.Custom.Performance.Tests/Microsoft.Azure.Cosmos.Encryption.Custom.Performance.Tests.csproj b/Microsoft.Azure.Cosmos.Encryption.Custom/tests/Microsoft.Azure.Cosmos.Encryption.Custom.Performance.Tests/Microsoft.Azure.Cosmos.Encryption.Custom.Performance.Tests.csproj
index 4deb4d0edf..821014c014 100644
--- a/Microsoft.Azure.Cosmos.Encryption.Custom/tests/Microsoft.Azure.Cosmos.Encryption.Custom.Performance.Tests/Microsoft.Azure.Cosmos.Encryption.Custom.Performance.Tests.csproj
+++ b/Microsoft.Azure.Cosmos.Encryption.Custom/tests/Microsoft.Azure.Cosmos.Encryption.Custom.Performance.Tests/Microsoft.Azure.Cosmos.Encryption.Custom.Performance.Tests.csproj
@@ -3,7 +3,7 @@
   <PropertyGroup>
     <AssemblyName>Microsoft.Azure.Cosmos.Encryption.Custom.Performance.Tests</AssemblyName>
     <OutputType>Exe</OutputType>
-    <TargetFrameworks>net6</TargetFrameworks>
+    <TargetFrameworks>net8.0</TargetFrameworks>
     <ImplicitUsings>enable</ImplicitUsings>
     <Nullable>enable</Nullable>
   </PropertyGroup>
diff --git a/Microsoft.Azure.Cosmos.Encryption.Custom/tests/Microsoft.Azure.Cosmos.Encryption.Custom.Tests/Microsoft.Azure.Cosmos.Encryption.Custom.Tests.csproj b/Microsoft.Azure.Cosmos.Encryption.Custom/tests/Microsoft.Azure.Cosmos.Encryption.Custom.Tests/Microsoft.Azure.Cosmos.Encryption.Custom.Tests.csproj
index eee64aada9..7e1f7d48fe 100644
--- a/Microsoft.Azure.Cosmos.Encryption.Custom/tests/Microsoft.Azure.Cosmos.Encryption.Custom.Tests/Microsoft.Azure.Cosmos.Encryption.Custom.Tests.csproj
+++ b/Microsoft.Azure.Cosmos.Encryption.Custom/tests/Microsoft.Azure.Cosmos.Encryption.Custom.Tests/Microsoft.Azure.Cosmos.Encryption.Custom.Tests.csproj
@@ -4,7 +4,7 @@
     <IsTestProject>true</IsTestProject>
     <TreatWarningsAsErrors>true</TreatWarningsAsErrors>
     <Platform>AnyCPU</Platform>
-    <TargetFramework>net6.0</TargetFramework>
+    <TargetFrameworks>net6.0;net8.0</TargetFrameworks>
     <IsPackable>false</IsPackable>
     <GenerateAssemblyInfo>false</GenerateAssemblyInfo>
     <RootNamespace>Microsoft.Azure.Cosmos.Encryption.Tests</RootNamespace>
diff --git a/Microsoft.Azure.Cosmos/tests/Microsoft.Azure.Cosmos.Tests/Contracts/ContractEnforcement.cs b/Microsoft.Azure.Cosmos/tests/Microsoft.Azure.Cosmos.Tests/Contracts/ContractEnforcement.cs
index c58109d65b..84bd8c63c1 100644
--- a/Microsoft.Azure.Cosmos/tests/Microsoft.Azure.Cosmos.Tests/Contracts/ContractEnforcement.cs
+++ b/Microsoft.Azure.Cosmos/tests/Microsoft.Azure.Cosmos.Tests/Contracts/ContractEnforcement.cs
@@ -14,7 +14,7 @@
 
     public class ContractEnforcement
     {
-        private static readonly InvariantComparer invariantComparer = new InvariantComparer();
+        private static readonly InvariantComparer invariantComparer = new ();
 
         private static Assembly GetAssemblyLocally(string name)
         {
@@ -91,7 +91,10 @@ private static string GenerateNameWithClassAttributes(Type type)
                 $"{nameof(type.IsValueType)}:{(type.IsValueType ? bool.TrueString : bool.FalseString)};" +
                 $"{nameof(type.IsNested)}:{(type.IsNested ? bool.TrueString : bool.FalseString)};" +
                 $"{nameof(type.IsGenericType)}:{(type.IsGenericType ? bool.TrueString : bool.FalseString)};" +
+#pragma warning disable SYSLIB0050 // 'Type.IsSerializable' is obsolete: 'Formatter-based serialization is obsolete and should not be used.
                 $"{nameof(type.IsSerializable)}:{(type.IsSerializable ? bool.TrueString : bool.FalseString)}";
+#pragma warning restore SYSLIB0050 // 'Type.IsSerializable' is obsolete: 'Formatter-based serialization is obsolete and should not be used.
+
         }
 
         private static string GenerateNameWithMethodAttributes(MethodInfo methodInfo)
@@ -241,7 +244,7 @@ public static void ValidatePreviewContractContainBreakingChanges(
 
         public static string GetCurrentContract(string dllName)
         {
-            TypeTree locally = new TypeTree(typeof(object));
+            TypeTree locally = new (typeof(object));
             Assembly assembly = ContractEnforcement.GetAssemblyLocally(dllName);
             Type[] exportedTypes = assembly.GetExportedTypes();
             ContractEnforcement.BuildTypeTree(locally, exportedTypes);
@@ -252,13 +255,13 @@ public static string GetCurrentContract(string dllName)
 
         public static string GetCurrentTelemetryContract(string dllName)
         {
-            List<string> nonTelemetryModels = new List<string>
+            List<string> nonTelemetryModels = new()
             {
                 "AzureVMMetadata",
                 "Compute"
             };
 
-            TypeTree locally = new TypeTree(typeof(object));
+            TypeTree locally = new (typeof(object));
             Assembly assembly = ContractEnforcement.GetAssemblyLocally(dllName);
             Type[] exportedTypes = assembly.GetTypes().Where(t => 
                                                                 t!= null && 
@@ -328,7 +331,10 @@ public static void ValidateJsonAreSame(string baselineJson, string currentJson)
 
         private class InvariantComparer : IComparer<string>
         {
-            public int Compare(string a, string b) => Comparer.DefaultInvariant.Compare(a, b);
+            public int Compare(string a, string b)
+            {
+                return Comparer.DefaultInvariant.Compare(a, b);
+            }
         }
     }
 }