diff --git a/Microsoft.Azure.Cosmos/src/CosmosClientOptions.cs b/Microsoft.Azure.Cosmos/src/CosmosClientOptions.cs
index 2c6aca0f3a..21df876c68 100644
--- a/Microsoft.Azure.Cosmos/src/CosmosClientOptions.cs
+++ b/Microsoft.Azure.Cosmos/src/CosmosClientOptions.cs
@@ -11,11 +11,11 @@ namespace Microsoft.Azure.Cosmos
     using System.Linq;
     using System.Net;
     using System.Net.Http;
+    using System.Net.Http.Headers;
     using Microsoft.Azure.Cosmos.Fluent;
     using Microsoft.Azure.Documents;
     using Microsoft.Azure.Documents.Client;
     using Newtonsoft.Json;
-    using Telemetry;
 
     /// <summary>
     /// Defines all the configurable options that the CosmosClient requires.
@@ -69,6 +69,7 @@ public class CosmosClientOptions
         private PortReuseMode? portReuseMode;
         private IWebProxy webProxy;
         private Func<HttpClient> httpClientFactory;
+        private string applicationName;
 
         /// <summary>
         /// Creates a new CosmosClientOptions
@@ -90,7 +91,24 @@ public CosmosClientOptions()
         /// <remarks>
         /// Setting this property after sending any request won't have any effect.
         /// </remarks>
-        public string ApplicationName { get; set; }
+        public string ApplicationName
+        {
+            get => this.applicationName;
+            set
+            {
+                try
+                {
+                    HttpRequestMessage dummyMessage = new HttpRequestMessage();
+                    dummyMessage.Headers.Add(HttpConstants.HttpHeaders.UserAgent, value);
+                }
+                catch (FormatException fme)
+                {
+                    throw new ArgumentException($"Application name '{value}' is invalid.", fme);
+                }
+
+                this.applicationName = value;
+            }
+        }
 
         /// <summary>
         /// Get or set session container for the client
diff --git a/Microsoft.Azure.Cosmos/tests/Microsoft.Azure.Cosmos.Tests/BaselineTest/TestBaseline/PassThroughQueryBaselineTests.NegativePassThroughOutput.xml b/Microsoft.Azure.Cosmos/tests/Microsoft.Azure.Cosmos.Tests/BaselineTest/TestBaseline/PassThroughQueryBaselineTests.NegativePassThroughOutput.xml
new file mode 100644
index 0000000000..e7e4d603fc
--- /dev/null
+++ b/Microsoft.Azure.Cosmos/tests/Microsoft.Azure.Cosmos.Tests/BaselineTest/TestBaseline/PassThroughQueryBaselineTests.NegativePassThroughOutput.xml
@@ -0,0 +1,41 @@
+<Results>
+  <Result>
+    <Input>
+      <Description>Null Partition Key Value</Description>
+      <Query>SELECT * FROM c</Query>
+      <PartitionKeys>
+        <Key>/pk</Key>
+      </PartitionKeys>
+      <PartitionKeyType>Hash</PartitionKeyType>
+    </Input>
+    <Output>
+      <ExecuteAsPassThrough>false</ExecuteAsPassThrough>
+    </Output>
+  </Result>
+  <Result>
+    <Input>
+      <Description>None Partition Key Value</Description>
+      <Query>SELECT * FROM c</Query>
+      <PartitionKeys>
+        <Key>/pk</Key>
+      </PartitionKeys>
+      <PartitionKeyType>Hash</PartitionKeyType>
+    </Input>
+    <Output>
+      <ExecuteAsPassThrough>false</ExecuteAsPassThrough>
+    </Output>
+  </Result>
+  <Result>
+    <Input>
+      <Description>C# Null Partition Key Value</Description>
+      <Query>SELECT * FROM c</Query>
+      <PartitionKeys>
+        <Key>/pk</Key>
+      </PartitionKeys>
+      <PartitionKeyType>Hash</PartitionKeyType>
+    </Input>
+    <Output>
+      <ExecuteAsPassThrough>false</ExecuteAsPassThrough>
+    </Output>
+  </Result>
+</Results>
\ No newline at end of file
diff --git a/Microsoft.Azure.Cosmos/tests/Microsoft.Azure.Cosmos.Tests/BaselineTest/TestBaseline/PassThroughQueryBaselineTests.PositivePassThroughOutput.xml b/Microsoft.Azure.Cosmos/tests/Microsoft.Azure.Cosmos.Tests/BaselineTest/TestBaseline/PassThroughQueryBaselineTests.PositivePassThroughOutput.xml
new file mode 100644
index 0000000000..94ed03c8b9
--- /dev/null
+++ b/Microsoft.Azure.Cosmos/tests/Microsoft.Azure.Cosmos.Tests/BaselineTest/TestBaseline/PassThroughQueryBaselineTests.PositivePassThroughOutput.xml
@@ -0,0 +1,41 @@
+<Results>
+  <Result>
+    <Input>
+      <Description>Partition Key + Value and Distinct</Description>
+      <Query>SELECT DISTINCT c.key FROM c</Query>
+      <PartitionKeys>
+        <Key>/pk</Key>
+      </PartitionKeys>
+      <PartitionKeyType>Hash</PartitionKeyType>
+    </Input>
+    <Output>
+      <ExecuteAsPassThrough>true</ExecuteAsPassThrough>
+    </Output>
+  </Result>
+  <Result>
+    <Input>
+      <Description>Partition Key + Value and Min Aggregate</Description>
+      <Query>SELECT VALUE MIN(c.key) FROM c</Query>
+      <PartitionKeys>
+        <Key>/pk</Key>
+      </PartitionKeys>
+      <PartitionKeyType>Hash</PartitionKeyType>
+    </Input>
+    <Output>
+      <ExecuteAsPassThrough>true</ExecuteAsPassThrough>
+    </Output>
+  </Result>
+  <Result>
+    <Input>
+      <Description>Partition Key + Value Fields</Description>
+      <Query>SELECT c.key FROM c</Query>
+      <PartitionKeys>
+        <Key>/pk</Key>
+      </PartitionKeys>
+      <PartitionKeyType>Hash</PartitionKeyType>
+    </Input>
+    <Output>
+      <ExecuteAsPassThrough>true</ExecuteAsPassThrough>
+    </Output>
+  </Result>
+</Results>
\ No newline at end of file
diff --git a/Microsoft.Azure.Cosmos/tests/Microsoft.Azure.Cosmos.Tests/Contracts/DotNetSDKAPI.json b/Microsoft.Azure.Cosmos/tests/Microsoft.Azure.Cosmos.Tests/Contracts/DotNetSDKAPI.json
index 1a69454b04..4e18b8084b 100644
--- a/Microsoft.Azure.Cosmos/tests/Microsoft.Azure.Cosmos.Tests/Contracts/DotNetSDKAPI.json
+++ b/Microsoft.Azure.Cosmos/tests/Microsoft.Azure.Cosmos.Tests/Contracts/DotNetSDKAPI.json
@@ -2896,11 +2896,9 @@
           "Attributes": [],
           "MethodInfo": "System.String ApplicationRegion;CanRead:True;CanWrite:True;System.String get_ApplicationRegion();IsAbstract:False;IsStatic:False;IsVirtual:False;IsGenericMethod:False;IsConstructor:False;IsFinal:False;Void set_ApplicationRegion(System.String);IsAbstract:False;IsStatic:False;IsVirtual:False;IsGenericMethod:False;IsConstructor:False;IsFinal:False;"
         },
-        "System.String get_ApplicationName()[System.Runtime.CompilerServices.CompilerGeneratedAttribute()]": {
+        "System.String get_ApplicationName()": {
           "Type": "Method",
-          "Attributes": [
-            "CompilerGeneratedAttribute"
-          ],
+          "Attributes": [],
           "MethodInfo": "System.String get_ApplicationName();IsAbstract:False;IsStatic:False;IsVirtual:False;IsGenericMethod:False;IsConstructor:False;IsFinal:False;"
         },
         "System.String get_ApplicationRegion()[System.Runtime.CompilerServices.CompilerGeneratedAttribute()]": {
@@ -2934,11 +2932,9 @@
           ],
           "MethodInfo": "Void set_AllowBulkExecution(Boolean);IsAbstract:False;IsStatic:False;IsVirtual:False;IsGenericMethod:False;IsConstructor:False;IsFinal:False;"
         },
-        "Void set_ApplicationName(System.String)[System.Runtime.CompilerServices.CompilerGeneratedAttribute()]": {
+        "Void set_ApplicationName(System.String)": {
           "Type": "Method",
-          "Attributes": [
-            "CompilerGeneratedAttribute"
-          ],
+          "Attributes": [],
           "MethodInfo": "Void set_ApplicationName(System.String);IsAbstract:False;IsStatic:False;IsVirtual:False;IsGenericMethod:False;IsConstructor:False;IsFinal:False;"
         },
         "Void set_ApplicationPreferredRegions(System.Collections.Generic.IReadOnlyList`1[System.String])[System.Runtime.CompilerServices.CompilerGeneratedAttribute()]": {
diff --git a/Microsoft.Azure.Cosmos/tests/Microsoft.Azure.Cosmos.Tests/CosmosClientOptionsUnitTests.cs b/Microsoft.Azure.Cosmos/tests/Microsoft.Azure.Cosmos.Tests/CosmosClientOptionsUnitTests.cs
index cf2a2083ce..ef6c70561c 100644
--- a/Microsoft.Azure.Cosmos/tests/Microsoft.Azure.Cosmos.Tests/CosmosClientOptionsUnitTests.cs
+++ b/Microsoft.Azure.Cosmos/tests/Microsoft.Azure.Cosmos.Tests/CosmosClientOptionsUnitTests.cs
@@ -539,6 +539,33 @@ public void WithQuorumReadWithEventualConsistencyAccount()
             Assert.IsTrue(cosmosClientOptions.EnableUpgradeConsistencyToLocalQuorum);
         }
 
+        [TestMethod]
+        public void InvalidApplicationNameCatchTest()
+        {
+
+            string[] illegalChars = new string[] { "<", ">", "\"", "{", "}", "\\", "[", "]", ";", ":", "@", "=", "(", ")", "," };
+            string baseName = "illegal";
+
+            foreach (string illegal in illegalChars)
+            {
+                Assert.ThrowsException<ArgumentException>(() => new CosmosClientOptions
+                {
+                    ApplicationName = baseName + illegal
+                });
+
+
+                Assert.ThrowsException<ArgumentException>(() => new CosmosClientOptions
+                {
+                    ApplicationName = illegal + baseName
+                });
+
+                Assert.ThrowsException<ArgumentException>(() => new CosmosClientOptions
+                {
+                    ApplicationName = illegal
+                });
+            }
+        }
+
         private class TestWebProxy : IWebProxy
         {
             public ICredentials Credentials { get; set; }