diff --git a/CHANGELOG.md b/CHANGELOG.md
index f0afb3cd4d..88fbc334d2 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -31,6 +31,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - Fixed a bug where allOf structure with one entry and properties would not be considered as inheritance case. [#4346](https://github.com/microsoft/kiota/issues/4346)
 - Fixed a bug where some allOf scenarios would be missing properties if type object wasn't set on the schema. [#4074](https://github.com/microsoft/kiota/issues/4074)
 - Fixed a bug where schema with multiple allOf entries would incorrectly get merged to inherit from the first entry [#4428] (https://github.com/microsoft/kiota/issues/4428)
+- Fixes constructor generation for nullable properties that are initialized as null in C#,Java and PHP
 
 ## [1.14.0] - 2024-05-02
 
diff --git a/src/Kiota.Builder/Writers/CSharp/CodeMethodWriter.cs b/src/Kiota.Builder/Writers/CSharp/CodeMethodWriter.cs
index a34312b563..889e348f43 100644
--- a/src/Kiota.Builder/Writers/CSharp/CodeMethodWriter.cs
+++ b/src/Kiota.Builder/Writers/CSharp/CodeMethodWriter.cs
@@ -248,6 +248,12 @@ private void WriteConstructorBody(CodeClass parentClass, CodeMethod currentMetho
             {
                 defaultValue = $"{conventions.GetTypeString(propWithDefault.Type, currentMethod).TrimEnd('?')}.{defaultValue.Trim('"').CleanupSymbolName().ToFirstCharacterUpperCase()}";
             }
+            // avoid setting null as a string.
+            if (propWithDefault.Type.IsNullable &&
+                defaultValue.TrimQuotes().Equals(NullValueString, StringComparison.OrdinalIgnoreCase))
+            {
+                defaultValue = NullValueString;
+            }
             writer.WriteLine($"{propWithDefault.Name.ToFirstCharacterUpperCase()} = {defaultValue};");
         }
         if (parentClass.IsOfKind(CodeClassKind.RequestBuilder) &&
@@ -267,6 +273,8 @@ private void WriteConstructorBody(CodeClass parentClass, CodeMethod currentMetho
                                                                 .ToArray());
         }
     }
+
+    private const string NullValueString = "null";
     private string DefaultDeserializerValue => $"new Dictionary<string, Action<{conventions.ParseNodeInterfaceName}>>";
     private void WriteDeserializerBody(bool shouldHide, CodeMethod codeElement, CodeClass parentClass, LanguageWriter writer)
     {
diff --git a/src/Kiota.Builder/Writers/Java/CodeMethodWriter.cs b/src/Kiota.Builder/Writers/Java/CodeMethodWriter.cs
index 8bf41ca027..3c9432bb58 100644
--- a/src/Kiota.Builder/Writers/Java/CodeMethodWriter.cs
+++ b/src/Kiota.Builder/Writers/Java/CodeMethodWriter.cs
@@ -358,6 +358,12 @@ private void WriteConstructorBody(CodeClass parentClass, CodeMethod currentMetho
             {
                 defaultValue = $"{enumDefinition.Name}.forValue({defaultValue})";
             }
+            // avoid setting null as a string.
+            if (propWithDefault.Type.IsNullable &&
+                defaultValue.TrimQuotes().Equals(NullValueString, StringComparison.OrdinalIgnoreCase))
+            {
+                defaultValue = NullValueString;
+            }
             writer.WriteLine($"this.{setterName}({defaultValue});");
         }
         if (parentClass.IsOfKind(CodeClassKind.RequestBuilder) &&
@@ -376,6 +382,7 @@ private void WriteConstructorBody(CodeClass parentClass, CodeMethod currentMetho
                                                                 .ToArray());
         }
     }
+    private const string NullValueString = "null";
     private static void WriteSetterBody(CodeMethod codeElement, LanguageWriter writer, CodeClass parentClass)
     {
         if (parentClass.GetBackingStoreProperty() is not CodeProperty backingStore || (codeElement.AccessedProperty?.IsOfKind(CodePropertyKind.BackingStore) ?? false))
diff --git a/src/Kiota.Builder/Writers/Php/CodeMethodWriter.cs b/src/Kiota.Builder/Writers/Php/CodeMethodWriter.cs
index 9fd505b322..4a96bd3eec 100644
--- a/src/Kiota.Builder/Writers/Php/CodeMethodWriter.cs
+++ b/src/Kiota.Builder/Writers/Php/CodeMethodWriter.cs
@@ -150,10 +150,17 @@ private void WriteModelConstructorBody(CodeClass parentClass, LanguageWriter wri
             {
                 defaultValue = $"new {enumDefinition.Name.ToFirstCharacterUpperCase()}({defaultValue})";
             }
+            // avoid setting null as a string.
+            if (propWithDefault.Type.IsNullable &&
+                defaultValue.TrimQuotes().Equals(NullValueString, StringComparison.OrdinalIgnoreCase))
+            {
+                defaultValue = NullValueString;
+            }
             writer.WriteLine($"$this->{setterName}({defaultValue});");
         }
     }
 
+    private const string NullValueString = "null";
     private void WriteRequestBuilderConstructorBody(CodeClass parentClass, CodeMethod currentMethod, LanguageWriter writer)
     {
         foreach (var propWithDefault in parentClass.GetPropertiesOfKind(
diff --git a/tests/Kiota.Builder.Tests/Writers/CSharp/CodeMethodWriterTests.cs b/tests/Kiota.Builder.Tests/Writers/CSharp/CodeMethodWriterTests.cs
index 50a5621c59..06fdbf7d21 100644
--- a/tests/Kiota.Builder.Tests/Writers/CSharp/CodeMethodWriterTests.cs
+++ b/tests/Kiota.Builder.Tests/Writers/CSharp/CodeMethodWriterTests.cs
@@ -1442,12 +1442,26 @@ public void WritesConstructor()
                 Name = "string"
             },
         });
+        var defaultValueNull = "\"null\"";
+        var nullPropName = "propWithDefaultNullValue";
+        parentClass.AddProperty(new CodeProperty
+        {
+            Name = nullPropName,
+            DefaultValue = defaultValueNull,
+            Kind = CodePropertyKind.Custom,
+            Type = new CodeType
+            {
+                Name = "int",
+                IsNullable = true
+            }
+        });
         writer.Write(method);
         var result = tw.ToString();
         Assert.Contains("<summary>", result);
         Assert.Contains("<see cref=", result);
         Assert.Contains(parentClass.Name.ToFirstCharacterUpperCase(), result);
         Assert.Contains($"{propName.ToFirstCharacterUpperCase()} = {defaultValue}", result);
+        Assert.Contains($"{nullPropName.ToFirstCharacterUpperCase()} = {defaultValueNull.TrimQuotes()}", result);
     }
     [Fact]
     public void WritesWithUrl()
diff --git a/tests/Kiota.Builder.Tests/Writers/Java/CodeMethodWriterTests.cs b/tests/Kiota.Builder.Tests/Writers/Java/CodeMethodWriterTests.cs
index dca1b6850f..e8f95c3bed 100644
--- a/tests/Kiota.Builder.Tests/Writers/Java/CodeMethodWriterTests.cs
+++ b/tests/Kiota.Builder.Tests/Writers/Java/CodeMethodWriterTests.cs
@@ -1787,6 +1787,19 @@ public void WritesConstructor()
                 Name = "String"
             }
         });
+        var defaultValueNull = "\"null\"";
+        var nullPropName = "propWithDefaultNullValue";
+        parentClass.AddProperty(new CodeProperty
+        {
+            Name = nullPropName,
+            DefaultValue = defaultValueNull,
+            Kind = CodePropertyKind.Custom,
+            Type = new CodeType
+            {
+                Name = "int",
+                IsNullable = true
+            }
+        });
         AddRequestProperties();
         method.AddParameter(new CodeParameter
         {
@@ -1801,6 +1814,7 @@ public void WritesConstructor()
         var result = tw.ToString();
         Assert.Contains(parentClass.Name, result);
         Assert.Contains($"this.set{propName.ToFirstCharacterUpperCase()}({defaultValue})", result);
+        Assert.Contains($"this.set{nullPropName.ToFirstCharacterUpperCase()}({defaultValueNull.TrimQuotes()})", result);
         Assert.Contains("super", result);
     }
     [Fact]
diff --git a/tests/Kiota.Builder.Tests/Writers/Php/CodeMethodWriterTests.cs b/tests/Kiota.Builder.Tests/Writers/Php/CodeMethodWriterTests.cs
index b1233a7f84..1a9f409226 100644
--- a/tests/Kiota.Builder.Tests/Writers/Php/CodeMethodWriterTests.cs
+++ b/tests/Kiota.Builder.Tests/Writers/Php/CodeMethodWriterTests.cs
@@ -1125,7 +1125,19 @@ public async Task WriteConstructorBody()
             Type = new CodeType { Name = "countryCode", TypeDefinition = countryCode }
         };
         parentClass.AddProperty(propWithDefaultValue, enumProp);
-
+        var defaultValueNull = "\"null\"";
+        var nullPropName = "propWithDefaultNullValue";
+        parentClass.AddProperty(new CodeProperty
+        {
+            Name = nullPropName,
+            DefaultValue = defaultValueNull,
+            Kind = CodePropertyKind.Custom,
+            Type = new CodeType
+            {
+                Name = "int",
+                IsNullable = true
+            }
+        });
         await ILanguageRefiner.Refine(new GenerationConfiguration { Language = GenerationLanguage.PHP }, root);
         _codeMethodWriter.WriteCodeElement(constructor, languageWriter);
         var result = stringWriter.ToString();
@@ -1133,6 +1145,7 @@ public async Task WriteConstructorBody()
         Assert.Contains("public function __construct", result);
         Assert.Contains("$this->setType('#microsoft.graph.entity')", result);
         Assert.Contains("$this->setCountryCode(new CountryCode('+254'));", result);
+        Assert.Contains("$this->setPropWithDefaultNullValue(null)", result);
     }
     [Fact]
     public void DoesNotWriteConstructorWithDefaultFromComposedType()