diff --git a/src/TALXIS.CLI.Platform.Dataverse.Data/EntityJsonConverter.cs b/src/TALXIS.CLI.Platform.Dataverse.Data/EntityJsonConverter.cs
index 971a2fa5..d5870507 100644
--- a/src/TALXIS.CLI.Platform.Dataverse.Data/EntityJsonConverter.cs
+++ b/src/TALXIS.CLI.Platform.Dataverse.Data/EntityJsonConverter.cs
@@ -177,6 +177,20 @@ public static JsonElement EntityToJson(Entity entity, bool includeAnnotations =
                     if (element.TryGetInt32(out var singleVal))
                         return new OptionSetValueCollection { new OptionSetValue(singleVal) };
                 }
+                if (attrMeta is IntegerAttributeMetadata)
+                {
+                    if (element.TryGetInt32(out var intVal)) return intVal;
+                        
+
+                    var column = attrMeta.LogicalName ?? "whole number column";
+                    
+                    if (element.TryGetInt64(out var outOfRange))
+                        throw new ArgumentException(
+                            $"Value {outOfRange} for '{column}' is outside the valid whole number range ({int.MinValue} to {int.MaxValue}).");
+
+                    throw new ArgumentException(
+                        $"Value {element.GetRawText()} for '{column}' is not a valid whole number.");
+                }
 
                 // Default: try integer types first, then floating-point.
                 if (element.TryGetInt32(out var i32)) return i32;
diff --git a/tests/TALXIS.CLI.Tests/Environment/Platforms/Dataverse/EntityJsonConverterTests.cs b/tests/TALXIS.CLI.Tests/Environment/Platforms/Dataverse/EntityJsonConverterTests.cs
new file mode 100644
index 00000000..a452bb65
--- /dev/null
+++ b/tests/TALXIS.CLI.Tests/Environment/Platforms/Dataverse/EntityJsonConverterTests.cs
@@ -0,0 +1,95 @@
+using System;
+using System.Text.Json;
+using Microsoft.Xrm.Sdk;
+using Microsoft.Xrm.Sdk.Metadata;
+using TALXIS.CLI.Platform.Dataverse.Data;
+using Xunit;
+
+namespace TALXIS.CLI.Tests.Environment.Platforms.Dataverse;
+
+/// <summary>
+/// Unit tests for <see cref="EntityJsonConverter"/> value coercion, focused on
+/// whole-number (Int32) range handling so out-of-range values produce a clear
+/// message instead of a misleading SDK type-mismatch error.
+/// </summary>
+public class EntityJsonConverterTests
+{
+    private const string Entity = "txcv3_valv3rt1434";
+    private const string Column = "txcv3_wholenumplain";
+
+    private static EntityMetadata MetadataWith(AttributeMetadata attribute)
+    {
+        var meta = new EntityMetadata { LogicalName = Entity };
+        SetProp(meta, nameof(EntityMetadata.Attributes), new[] { attribute });
+        return meta;
+    }
+
+    private static AttributeMetadata IntegerColumn(string logicalName = Column)
+    {
+        var attr = new IntegerAttributeMetadata();
+        SetProp(attr, nameof(AttributeMetadata.LogicalName), logicalName);
+        return attr;
+    }
+
+    private static AttributeMetadata BigIntColumn(string logicalName)
+    {
+        var attr = new BigIntAttributeMetadata();
+        SetProp(attr, nameof(AttributeMetadata.LogicalName), logicalName);
+        return attr;
+    }
+
+    // Xrm SDK metadata properties expose non-public setters — reach them by reflection.
+    private static void SetProp(object target, string name, object? value)
+        => target.GetType().GetProperty(name)!.SetValue(target, value);
+
+    private static Entity Convert(EntityMetadata metadata, string json)
+        => EntityJsonConverter.JsonToEntity(Entity, JsonDocument.Parse(json).RootElement, metadata);
+
+    [Fact]
+    public void WholeNumber_WithinInt32Range_StoredAsInt()
+    {
+        var entity = Convert(MetadataWith(IntegerColumn()), $"{{\"{Column}\":2000000000}}");
+
+        Assert.Equal(2000000000, Assert.IsType<int>(entity[Column]));
+    }
+
+    [Fact]
+    public void WholeNumber_AboveInt32Max_ThrowsRangeErrorWithValueAndColumn()
+    {
+        var ex = Assert.Throws<ArgumentException>(
+            () => Convert(MetadataWith(IntegerColumn()), $"{{\"{Column}\":3000000000}}"));
+
+        Assert.Contains("3000000000", ex.Message);
+        Assert.Contains(Column, ex.Message);
+        Assert.Contains("range", ex.Message, StringComparison.OrdinalIgnoreCase);
+        // The misleading SDK wording must not leak through.
+        Assert.DoesNotContain("Incorrect attribute value type", ex.Message);
+    }
+
+    [Fact]
+    public void WholeNumber_BelowInt32Min_ThrowsRangeError()
+    {
+        var ex = Assert.Throws<ArgumentException>(
+            () => Convert(MetadataWith(IntegerColumn()), $"{{\"{Column}\":-3000000000}}"));
+
+        Assert.Contains("-3000000000", ex.Message);
+    }
+
+    [Fact]
+    public void WholeNumber_NonInteger_ThrowsFormatError()
+    {
+        var ex = Assert.Throws<ArgumentException>(
+            () => Convert(MetadataWith(IntegerColumn()), $"{{\"{Column}\":1.5}}"));
+
+        Assert.Contains("whole number", ex.Message, StringComparison.OrdinalIgnoreCase);
+    }
+
+    [Fact]
+    public void BigInt_AboveInt32Max_StoredAsLong()
+    {
+        const string column = "txcv3_bignum";
+        var entity = Convert(MetadataWith(BigIntColumn(column)), $"{{\"{column}\":3000000000}}");
+
+        Assert.Equal(3000000000L, Assert.IsType<long>(entity[column]));
+    }
+}