diff --git a/docs/samples/Microsoft.ML.Samples/Dynamic/Transforms/CustomMappingSaveAndLoad.cs b/docs/samples/Microsoft.ML.Samples/Dynamic/Transforms/CustomMappingSaveAndLoad.cs
index f2d97b70eb..57b52c342c 100644
--- a/docs/samples/Microsoft.ML.Samples/Dynamic/Transforms/CustomMappingSaveAndLoad.cs
+++ b/docs/samples/Microsoft.ML.Samples/Dynamic/Transforms/CustomMappingSaveAndLoad.cs
@@ -45,6 +45,7 @@ public static void Example()
             // the custom action is defined needs to be registered in the
             // environment. The following registers the assembly where
             // IsUnderThirtyCustomAction is defined.    
+            // This is necessary only in versions v1.5-preview2 and earlier
             mlContext.ComponentCatalog.RegisterAssembly(typeof(
                 IsUnderThirtyCustomAction).Assembly);
 
diff --git a/src/Microsoft.ML.Transforms/CustomMappingCatalog.cs b/src/Microsoft.ML.Transforms/CustomMappingCatalog.cs
index 819a518188..c918302d5e 100644
--- a/src/Microsoft.ML.Transforms/CustomMappingCatalog.cs
+++ b/src/Microsoft.ML.Transforms/CustomMappingCatalog.cs
@@ -25,7 +25,7 @@ public static class CustomMappingCatalog
         /// If the resulting transformer needs to be save-able, the class defining <paramref name="mapAction"/> should implement
         /// <see cref="CustomMappingFactory{TSrc, TDst}"/> and needs to be decorated with
         /// <see cref="CustomMappingFactoryAttributeAttribute"/> with the provided <paramref name="contractName"/>.
-        /// The assembly containing the class should be registered in the environment where it is loaded back
+        /// In versions v1.5-preview2 and earlier, the assembly containing the class should be registered in the environment where it is loaded back
         /// using <see cref="ComponentCatalog.RegisterAssembly(System.Reflection.Assembly, bool)"/>.</param>
         /// <param name="contractName">The contract name, used by ML.NET for loading the model.
         /// If <see langword="null"/> is specified, resulting transformer would not be save-able.</param>
diff --git a/src/Microsoft.ML.Transforms/CustomMappingTransformer.cs b/src/Microsoft.ML.Transforms/CustomMappingTransformer.cs
index 7a781128a5..03c55c8c58 100644
--- a/src/Microsoft.ML.Transforms/CustomMappingTransformer.cs
+++ b/src/Microsoft.ML.Transforms/CustomMappingTransformer.cs
@@ -22,6 +22,7 @@ public sealed class CustomMappingTransformer<TSrc, TDst> : ITransformer
         private readonly IHost _host;
         private readonly Action<TSrc, TDst> _mapAction;
         private readonly string _contractName;
+        private readonly string _contractAssembly;
 
         internal InternalSchemaDefinition AddedSchema { get; }
         internal SchemaDefinition InputSchemaDefinition { get; }
@@ -58,6 +59,7 @@ internal CustomMappingTransformer(IHostEnvironment env, Action<TSrc, TDst> mapAc
                : InternalSchemaDefinition.Create(typeof(TDst), outputSchemaDefinition);
 
             _contractName = contractName;
+            _contractAssembly = _mapAction.Method.DeclaringType.Assembly.FullName;
             AddedSchema = outSchema;
         }
 
@@ -67,7 +69,7 @@ internal void SaveModel(ModelSaveContext ctx)
         {
             if (_contractName == null)
                 throw _host.Except("Empty contract name for a transform: the transform cannot be saved");
-            LambdaTransform.SaveCustomTransformer(_host, ctx, _contractName);
+            LambdaTransform.SaveCustomTransformer(_host, ctx, _contractName, _contractAssembly);
         }
 
         /// <summary>
diff --git a/src/Microsoft.ML.Transforms/LambdaTransform.cs b/src/Microsoft.ML.Transforms/LambdaTransform.cs
index 4ba05ee4f8..88de4a68e1 100644
--- a/src/Microsoft.ML.Transforms/LambdaTransform.cs
+++ b/src/Microsoft.ML.Transforms/LambdaTransform.cs
@@ -4,6 +4,7 @@
 
 using System;
 using System.IO;
+using System.Reflection;
 using System.Text;
 using Microsoft.ML;
 using Microsoft.ML.Data;
@@ -40,14 +41,17 @@ private static VersionInfo GetVersionInfo()
         {
             return new VersionInfo(
                 modelSignature: "CUSTOMXF",
-                verWrittenCur: 0x00010001,
-                verReadableCur: 0x00010001,
+                //verWrittenCur: 0x00010001,  // Initial
+                verWrittenCur: 0x00010002,  // Added name of assembly in which the contractName is present
+                verReadableCur: 0x00010002,
                 verWeCanReadBack: 0x00010001,
                 loaderSignature: LoaderSignature,
                 loaderAssemblyName: typeof(LambdaTransform).Assembly.FullName);
         }
 
-        internal static void SaveCustomTransformer(IExceptionContext ectx, ModelSaveContext ctx, string contractName)
+        private const uint VerAssemblyNameSaved = 0x00010002;
+
+        internal static void SaveCustomTransformer(IExceptionContext ectx, ModelSaveContext ctx, string contractName, string contractAssembly)
         {
             ectx.CheckValue(ctx, nameof(ctx));
             ectx.CheckValue(contractName, nameof(contractName));
@@ -56,6 +60,7 @@ internal static void SaveCustomTransformer(IExceptionContext ectx, ModelSaveCont
             ctx.SetVersionInfo(GetVersionInfo());
 
             ctx.SaveString(contractName);
+            ctx.SaveString(contractAssembly);
         }
 
         // Factory for SignatureLoadModel.
@@ -66,6 +71,12 @@ private static ITransformer Create(IHostEnvironment env, ModelLoadContext ctx)
             ctx.CheckAtModel(GetVersionInfo());
 
             var contractName = ctx.LoadString();
+            if (ctx.Header.ModelVerWritten >= VerAssemblyNameSaved)
+            {
+                var contractAssembly = ctx.LoadString();
+                Assembly assembly = Assembly.Load(contractAssembly);
+                env.ComponentCatalog.RegisterAssembly(assembly);
+            }
 
             object factoryObject = env.ComponentCatalog.GetExtensionValue(env, typeof(CustomMappingFactoryAttributeAttribute), contractName);
             if (!(factoryObject is ICustomMappingFactory mappingFactory))
diff --git a/test/Microsoft.ML.Core.Tests/UnitTests/TestCustomTypeRegister.cs b/test/Microsoft.ML.Core.Tests/UnitTests/TestCustomTypeRegister.cs
index b0660bfe08..3bfa01c6b7 100644
--- a/test/Microsoft.ML.Core.Tests/UnitTests/TestCustomTypeRegister.cs
+++ b/test/Microsoft.ML.Core.Tests/UnitTests/TestCustomTypeRegister.cs
@@ -4,6 +4,7 @@
 
 using System;
 using System.Collections.Generic;
+using System.IO;
 using System.Linq;
 using Microsoft.ML.Data;
 using Microsoft.ML.Transforms;
@@ -151,7 +152,7 @@ public SuperAlienHero()
 
         /// <summary>
         /// A mapping from <see cref="AlienHero"/> to <see cref="SuperAlienHero"/>. It is used to create a
-        /// <see cref="CustomMappingEstimator{TSrc, TDst}"/> in <see cref="RegisterTypeWithAttribute()"/>.
+        /// <see cref="CustomMappingEstimator{TSrc, TDst}"/> in <see cref="RegisterTypeWithAttribute(bool)"/>.
         /// </summary>
         [CustomMappingFactoryAttribute("LambdaAlienHero")]
         private class AlienFusionProcess : CustomMappingFactory<AlienHero, SuperAlienHero>
@@ -171,8 +172,10 @@ public override Action<AlienHero, SuperAlienHero> GetMapping()
             }
         }
 
-        [Fact]
-        public void RegisterTypeWithAttribute()
+        [Theory]
+        [InlineData(true)]
+        [InlineData(false)]
+        public void RegisterTypeWithAttribute(bool saveModel)
         {
             // Build in-memory data.
             var tribe = new List<AlienHero>() { new AlienHero("ML.NET", 2, 1000, 2000, 3000, 4000, 5000, 6000, 7000) };
@@ -184,6 +187,13 @@ public void RegisterTypeWithAttribute()
             var tribeTransformed = model.Transform(tribeDataView);
             var tribeEnumerable = ML.Data.CreateEnumerable<SuperAlienHero>(tribeTransformed, false).ToList();
 
+            ITransformer modelForPrediction = model;
+            if (saveModel)
+            {
+                ML.Model.Save(model, tribeDataView.Schema, "customTransform.zip");
+                modelForPrediction = ML.Model.Load("customTransform.zip", out var tribeDataViewSchema);
+            }
+
             // Make sure the pipeline output is correct.
             Assert.Equal(tribeEnumerable[0].Name, "Super " + tribe[0].Name);
             Assert.Equal(tribeEnumerable[0].Merged.Age, tribe[0].One.Age + tribe[0].Two.Age);
@@ -192,7 +202,7 @@ public void RegisterTypeWithAttribute()
             Assert.Equal(tribeEnumerable[0].Merged.HandCount, tribe[0].One.HandCount + tribe[0].Two.HandCount);
 
             // Build prediction engine from the trained pipeline.
-            var engine = ML.Model.CreatePredictionEngine<AlienHero, SuperAlienHero>(model);
+            var engine = ML.Model.CreatePredictionEngine<AlienHero, SuperAlienHero>(modelForPrediction);
             var alien = new AlienHero("TEN.LM", 1, 2, 3, 4, 5, 6, 7, 8);
             var superAlien = engine.Predict(alien);
 
@@ -202,6 +212,31 @@ public void RegisterTypeWithAttribute()
             Assert.Equal(superAlien.Merged.Height, alien.One.Height + alien.Two.Height);
             Assert.Equal(superAlien.Merged.Weight, alien.One.Weight + alien.Two.Weight);
             Assert.Equal(superAlien.Merged.HandCount, alien.One.HandCount + alien.Two.HandCount);
+
+            Done();
+        }
+
+        [Fact]
+        void TestCustomTransformBackcompat()
+        {
+            // With older versions, it is necessary to register the assembly
+            ML.ComponentCatalog.RegisterAssembly(typeof(AlienFusionProcess).Assembly);
+
+            var modelPath = Path.Combine(DataDir, "backcompat", "customTransform.zip");
+            var trainedModel = ML.Model.Load(modelPath, out var dataViewSchema);
+
+            var engine = ML.Model.CreatePredictionEngine<AlienHero, SuperAlienHero>(trainedModel);
+            var alien = new AlienHero("TEN.LM", 1, 2, 3, 4, 5, 6, 7, 8);
+            var superAlien = engine.Predict(alien);
+
+            // Make sure the prediction engine produces expected result.
+            Assert.Equal(superAlien.Name, "Super " + alien.Name);
+            Assert.Equal(superAlien.Merged.Age, alien.One.Age + alien.Two.Age);
+            Assert.Equal(superAlien.Merged.Height, alien.One.Height + alien.Two.Height);
+            Assert.Equal(superAlien.Merged.Weight, alien.One.Weight + alien.Two.Weight);
+            Assert.Equal(superAlien.Merged.HandCount, alien.One.HandCount + alien.Two.HandCount);
+
+            Done();
         }
 
         [Fact]
diff --git a/test/Microsoft.ML.Tests/ScenariosWithDirectInstantiation/TensorflowTests.cs b/test/Microsoft.ML.Tests/ScenariosWithDirectInstantiation/TensorflowTests.cs
index 08b7f38ee8..97f473dee6 100644
--- a/test/Microsoft.ML.Tests/ScenariosWithDirectInstantiation/TensorflowTests.cs
+++ b/test/Microsoft.ML.Tests/ScenariosWithDirectInstantiation/TensorflowTests.cs
@@ -1250,14 +1250,10 @@ public void TensorFlowStringTest()
         }
 
         [TensorFlowFact]
+        // This test hangs occasionally
+        [Trait("Category", "SkipInCI")]
         public void TensorFlowImageClassificationDefault()
         {
-            if (RuntimeInformation.IsOSPlatform(OSPlatform.Linux))
-            {
-                Output.WriteLine("TODO TEST_STABILITY: TensorFlowImageClassificationDefault hangs on Linux.");
-                return;
-            }
-
             string imagesDownloadFolderPath = Path.Combine(TensorFlowScenariosTestsFixture.assetsPath, "inputs",
                 "images");
 
@@ -1628,13 +1624,10 @@ internal void TensorFlowImageClassificationWithLRScheduling(LearningRateSchedule
         [TensorFlowTheory]
         [InlineData(ImageClassificationTrainer.EarlyStoppingMetric.Accuracy)]
         [InlineData(ImageClassificationTrainer.EarlyStoppingMetric.Loss)]
+        // This test hangs ocassionally
+        [Trait("Category", "SkipInCI")]
         public void TensorFlowImageClassificationEarlyStopping(ImageClassificationTrainer.EarlyStoppingMetric earlyStoppingMetric)
         {
-            if (RuntimeInformation.IsOSPlatform(OSPlatform.Linux))
-            {
-                Output.WriteLine("TODO TEST_STABILITY: TensorFlowImageClassificationEarlyStopping hangs on Linux.");
-                return;
-            }
             string imagesDownloadFolderPath = Path.Combine(TensorFlowScenariosTestsFixture.assetsPath, "inputs",
                 "images");
 
diff --git a/test/Microsoft.ML.Tests/Transformers/CustomMappingTests.cs b/test/Microsoft.ML.Tests/Transformers/CustomMappingTests.cs
index c4d9378024..d6e58b5ebc 100644
--- a/test/Microsoft.ML.Tests/Transformers/CustomMappingTests.cs
+++ b/test/Microsoft.ML.Tests/Transformers/CustomMappingTests.cs
@@ -44,8 +44,10 @@ public override Action<MyInput, MyOutput> GetMapping()
             }
         }
 
-        [Fact]
-        public void TestCustomTransformer()
+        [Theory]
+        [InlineData(true)]
+        [InlineData(false)]
+        public void TestCustomTransformer(bool registerAssembly)
         {
             string dataPath = GetDataPath("adult.tiny.with-schema.txt");
             var source = new MultiFileSource(dataPath);
@@ -62,17 +64,13 @@ public void TestCustomTransformer()
             var tempoEnv = new MLContext(1);
             var customEst = new CustomMappingEstimator<MyInput, MyOutput>(tempoEnv, MyLambda.MyAction, "MyLambda");
 
-            try
-            {
-                TestEstimatorCore(customEst, data);
-                Assert.True(false, "Cannot work without RegisterAssembly");
-            }
-            catch (InvalidOperationException ex)
-            {
-                if (!ex.IsMarked())
-                    throw;
-            }
-            ML.ComponentCatalog.RegisterAssembly(typeof(MyLambda).Assembly);
+            // Before 1.5-preview3 it was required to register the assembly. 
+            // Now, the assembly information is automatically saved in the model and the assembly is registered
+            // when loading.
+            // This tests the case that the CustomTransformer still works even if you explicitly register the assembly
+            if (registerAssembly)
+                ML.ComponentCatalog.RegisterAssembly(typeof(MyLambda).Assembly);
+
             TestEstimatorCore(customEst, data);
             transformedData = customEst.Fit(data).Transform(data);
 
diff --git a/test/data/backcompat/customTransform.zip b/test/data/backcompat/customTransform.zip
new file mode 100644
index 0000000000..967a43f0d5
Binary files /dev/null and b/test/data/backcompat/customTransform.zip differ