diff --git a/CHANGELOG.md b/CHANGELOG.md
index cb0ffe557..61b57907a 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,3 +1,12 @@
+6.3.1
+==
+
+## Bug Fixes
+
+- [Kotlin enum values not visible at runtime (#1560)](https://github.com/NativeScript/android-runtime/issues/1560)
+- [Code cache breaks HMR (#1554)](https://github.com/NativeScript/android-runtime/issues/1554)
+- [Worker memory leak in android (#1550)](https://github.com/NativeScript/android-runtime/issues/1550)
+
 6.3.0
 ==
 
diff --git a/package.json b/package.json
index 178af4c37..d9b7b3118 100644
--- a/package.json
+++ b/package.json
@@ -1,7 +1,7 @@
 {
   "name": "tns-android",
   "description": "NativeScript Runtime for Android",
-  "version": "6.3.0",
+  "version": "6.3.1",
   "repository": {
     "type": "git",
     "url": "https://github.com/NativeScript/android-runtime.git"
diff --git a/test-app/app/src/main/assets/app/mainpage.js b/test-app/app/src/main/assets/app/mainpage.js
index d4adf51d4..dfa8d5806 100644
--- a/test-app/app/src/main/assets/app/mainpage.js
+++ b/test-app/app/src/main/assets/app/mainpage.js
@@ -61,4 +61,5 @@ require("./tests/kotlin/delegation/testDelegationSupport");
 require("./tests/kotlin/objects/testObjectsSupport");
 require("./tests/kotlin/functions/testTopLevelFunctionsSupport");
 require("./tests/kotlin/extensions/testExtensionFunctionsSupport");
+require("./tests/kotlin/enums/testEnumsSupport");
 require("./tests/kotlin/access/testInternalLanguageFeaturesSupport");
\ No newline at end of file
diff --git a/test-app/app/src/main/assets/app/tests/kotlin/enums/testEnumsSupport.js b/test-app/app/src/main/assets/app/tests/kotlin/enums/testEnumsSupport.js
new file mode 100644
index 000000000..3ff0bd04d
--- /dev/null
+++ b/test-app/app/src/main/assets/app/tests/kotlin/enums/testEnumsSupport.js
@@ -0,0 +1,10 @@
+describe("Tests Kotlin extension functions support", function () {
+
+    it("Test Kotlin enum entries are accessible", function () {
+        var enumEntry = com.tns.tests.kotlin.enums.KotlinEnum.TEST_ENTRY;
+
+        expect(enumEntry).not.toBe(undefined);
+        expect(enumEntry).not.toBe(null);
+    });
+
+});
\ No newline at end of file
diff --git a/test-app/app/src/main/java/com/tns/tests/kotlin/enums/KotlinEnum.kt b/test-app/app/src/main/java/com/tns/tests/kotlin/enums/KotlinEnum.kt
new file mode 100644
index 000000000..4503bc553
--- /dev/null
+++ b/test-app/app/src/main/java/com/tns/tests/kotlin/enums/KotlinEnum.kt
@@ -0,0 +1,5 @@
+package com.tns.tests.kotlin.enums
+
+enum class KotlinEnum {
+    TEST_ENTRY
+}
\ No newline at end of file
diff --git a/test-app/build-tools/android-metadata-generator/src/src/com/telerik/metadata/parsing/kotlin/classes/KotlinClassDescriptor.kt b/test-app/build-tools/android-metadata-generator/src/src/com/telerik/metadata/parsing/kotlin/classes/KotlinClassDescriptor.kt
index 86289580c..eb42a1814 100644
--- a/test-app/build-tools/android-metadata-generator/src/src/com/telerik/metadata/parsing/kotlin/classes/KotlinClassDescriptor.kt
+++ b/test-app/build-tools/android-metadata-generator/src/src/com/telerik/metadata/parsing/kotlin/classes/KotlinClassDescriptor.kt
@@ -7,6 +7,7 @@ import com.telerik.metadata.parsing.NativeMethodDescriptor
 import com.telerik.metadata.parsing.NativePropertyDescriptor
 import com.telerik.metadata.parsing.bytecode.classes.NativeClassBytecodeDescriptor
 import com.telerik.metadata.parsing.kotlin.fields.KotlinCompanionFieldDescriptor
+import com.telerik.metadata.parsing.kotlin.fields.KotlinEnumFieldDescriptor
 import com.telerik.metadata.parsing.kotlin.fields.KotlinJvmFieldDescriptor
 import com.telerik.metadata.parsing.kotlin.metadata.MetadataAnnotation
 import com.telerik.metadata.parsing.kotlin.metadata.bytecode.BytecodeClassMetadataParser
@@ -36,7 +37,6 @@ class KotlinClassDescriptor(nativeClass: JavaClass, private val metadataAnnotati
 
     override val fields: Array<NativeFieldDescriptor> by lazy {
         val fields = ArrayList<NativeFieldDescriptor>()
-
         val meta = kotlinMetadata
         var kotlinMetadataProperties: Collection<KmProperty> = emptyList()
 
@@ -48,6 +48,12 @@ class KotlinClassDescriptor(nativeClass: JavaClass, private val metadataAnnotati
             if (possibleCompanionField.isPresent) {
                 fields.add(possibleCompanionField.get())
             }
+
+            if(metaClass.enumEntries.isNotEmpty()){
+                val enumFields = getEnumEntriesAsFields(nativeClass, metaClass.enumEntries)
+                fields.addAll(enumFields)
+            }
+
         } else if (meta is KotlinClassMetadata.FileFacade) {
             kotlinMetadataProperties = meta.toKmPackage().properties
         } else if (meta is KotlinClassMetadata.MultiFileClassPart) {
@@ -107,6 +113,20 @@ class KotlinClassDescriptor(nativeClass: JavaClass, private val metadataAnnotati
         return Optional.empty()
     }
 
+    private fun getEnumEntriesAsFields(nativeClass: JavaClass, metadataEnumEntries: Collection<String>): Collection<KotlinEnumFieldDescriptor> {
+        val bytecodeFields = nativeClass.fields
+
+        val matchingEnumFields = bytecodeFields
+                .filter {
+                    metadataEnumEntries.contains(it.name)
+                }
+                .map {
+                    KotlinEnumFieldDescriptor(it, isPublic, isInternal, isProtected)
+                }
+
+        return matchingEnumFields
+    }
+
     override val properties: Array<out NativePropertyDescriptor> by lazy {
         val metadata = kotlinMetadata
         if (metadata is KotlinClassMetadata.Class) {
diff --git a/test-app/build-tools/android-metadata-generator/src/src/com/telerik/metadata/parsing/kotlin/fields/KotlinEnumFieldDescriptor.kt b/test-app/build-tools/android-metadata-generator/src/src/com/telerik/metadata/parsing/kotlin/fields/KotlinEnumFieldDescriptor.kt
new file mode 100644
index 000000000..1fab52697
--- /dev/null
+++ b/test-app/build-tools/android-metadata-generator/src/src/com/telerik/metadata/parsing/kotlin/fields/KotlinEnumFieldDescriptor.kt
@@ -0,0 +1,9 @@
+package com.telerik.metadata.parsing.kotlin.fields
+
+import com.telerik.metadata.parsing.bytecode.fields.NativeFieldBytecodeDescriptor
+import org.apache.bcel.classfile.Field
+
+class KotlinEnumFieldDescriptor(field: Field,
+                                override val isPublic: Boolean,
+                                override val isInternal: Boolean,
+                                override val isProtected: Boolean) : NativeFieldBytecodeDescriptor(field)
\ No newline at end of file
diff --git a/test-app/runtime/src/main/cpp/JSONObjectHelper.cpp b/test-app/runtime/src/main/cpp/JSONObjectHelper.cpp
index 9ca78d5a2..a415e0c0a 100644
--- a/test-app/runtime/src/main/cpp/JSONObjectHelper.cpp
+++ b/test-app/runtime/src/main/cpp/JSONObjectHelper.cpp
@@ -7,33 +7,54 @@
 using namespace v8;
 using namespace tns;
 
-JSONObjectHelper::JSONObjectHelper()
-    : m_objectManager(nullptr), m_serializeFunc(nullptr) {
-}
-
-void JSONObjectHelper::CreateConvertFunctions(Isolate *isolate, const Local<Object> &global, ObjectManager* objectManager) {
-    m_objectManager = objectManager;
+void JSONObjectHelper::RegisterFromFunction(Isolate *isolate, Local<Value>& jsonObject) {
+    if (!jsonObject->IsFunction()) {
+        return;
+    }
 
-    m_serializeFunc = new Persistent<Function>(isolate, CreateSerializeFunc(isolate));
+    Isolate::Scope isolate_scope(isolate);
+    HandleScope handle_scope(isolate);
 
     Local<Context> context = isolate->GetCurrentContext();
+    Context::Scope context_scope(context);
 
-    Local<External> extData = External::New(isolate, this);
-    Local<Function> fromFunc = FunctionTemplate::New(isolate, ConvertCallbackStatic, extData)->GetFunction(context).ToLocalChecked();
-
-    Local<Function> jsonObjectFunc = global->Get(context, ArgConverter::ConvertToV8String(isolate, "org"))
-            .ToLocalChecked().As<Object>()->Get(context, ArgConverter::ConvertToV8String(isolate, "json"))
-            .ToLocalChecked().As<Object>()->Get(context, ArgConverter::ConvertToV8String(isolate, "JSONObject"))
-            .ToLocalChecked().As<Function>();
+    Local<Function> jsonObjectFunc =  jsonObject.As<Function>();
+    auto fromKey = ArgConverter::ConvertToV8String(isolate, "from");
+    if (jsonObjectFunc->Has(context, fromKey).FromMaybe(false)) {
+        return;
+    }
 
-    jsonObjectFunc->Set(context, ArgConverter::ConvertToV8String(isolate, "from"), fromFunc);
+    Persistent<Function>* serializeFunc = new Persistent<Function>(isolate, CreateSerializeFunc(context));
+    Local<External> extData = External::New(isolate, serializeFunc);
+    Local<Function> fromFunc;
+    bool ok = FunctionTemplate::New(isolate, ConvertCallbackStatic, extData)->GetFunction(context).ToLocal(&fromFunc);
+    assert(ok);
+    jsonObjectFunc->Set(context, fromKey, fromFunc);
 }
 
 void JSONObjectHelper::ConvertCallbackStatic(const FunctionCallbackInfo<Value>& info) {
     try {
         Local<External> extData = info.Data().As<External>();
-        auto thiz = reinterpret_cast<JSONObjectHelper*>(extData->Value());
-        thiz->ConvertCallback(info);
+        auto poSerializeFunc = reinterpret_cast<Persistent<Function>*>(extData->Value());
+        Isolate* isolate = info.GetIsolate();
+        Local<Function> serializeFunc = poSerializeFunc->Get(isolate);
+
+        if (info.Length() < 1) {
+            NativeScriptException nsEx(std::string("The \"from\" function expects one parameter"));
+            nsEx.ReThrowToV8();
+            return;
+        }
+
+        Local<Context> context = isolate->GetCurrentContext();
+
+        Local<Value> args[] = { info[0] };
+        Local<Value> result;
+        TryCatch tc(isolate);
+        if (!serializeFunc->Call(context, Undefined(isolate), 1, args).ToLocal(&result)) {
+            throw NativeScriptException(tc, "Error serializing to JSONObject");
+        }
+
+        info.GetReturnValue().Set(result);
     } catch (NativeScriptException& e) {
         e.ReThrowToV8();
     } catch (std::exception e) {
@@ -47,28 +68,7 @@ void JSONObjectHelper::ConvertCallbackStatic(const FunctionCallbackInfo<Value>&
     }
 }
 
-void JSONObjectHelper::ConvertCallback(const FunctionCallbackInfo<Value>& info) {
-    if (info.Length() < 1) {
-        NativeScriptException nsEx(std::string("The \"from\" function expects one parameter"));
-        nsEx.ReThrowToV8();
-        return;
-    }
-
-    Isolate* isolate = info.GetIsolate();
-    Local<Context> context = isolate->GetCurrentContext();
-
-    Local<Function> serializeFunc = m_serializeFunc->Get(isolate);
-    Local<Value> args[] = { info[0] };
-    Local<Value> result;
-    TryCatch tc(isolate);
-    if (!serializeFunc->Call(context, Undefined(isolate), 1, args).ToLocal(&result)) {
-        throw NativeScriptException(tc, "Error serializing to JSONObject");
-    }
-
-    info.GetReturnValue().Set(result);
-}
-
-Local<Function> JSONObjectHelper::CreateSerializeFunc(Isolate* isolate) {
+Local<Function> JSONObjectHelper::CreateSerializeFunc(Local<Context> context) {
     std::string source =
         "(() => function serialize(data) {"
         "    let store;"
@@ -102,7 +102,7 @@ Local<Function> JSONObjectHelper::CreateSerializeFunc(Isolate* isolate) {
         "    }"
         "})()";
 
-    Local<Context> context = isolate->GetCurrentContext();
+    Isolate* isolate = context->GetIsolate();
 
     Local<Script> script = Script::Compile(context, ArgConverter::ConvertToV8String(isolate, source)).ToLocalChecked();
 
diff --git a/test-app/runtime/src/main/cpp/JSONObjectHelper.h b/test-app/runtime/src/main/cpp/JSONObjectHelper.h
index 55294bdc6..1597e3551 100644
--- a/test-app/runtime/src/main/cpp/JSONObjectHelper.h
+++ b/test-app/runtime/src/main/cpp/JSONObjectHelper.h
@@ -2,20 +2,14 @@
 #define JSONOBJECTHELPER_H_
 
 #include "v8.h"
-#include "ObjectManager.h"
 
 namespace tns {
 
 class JSONObjectHelper {
 public:
-    JSONObjectHelper();
-    void CreateConvertFunctions(v8::Isolate* isolate, const v8::Local<v8::Object>& global, ObjectManager* objectManager);
+    static void RegisterFromFunction(v8::Isolate *isolate, v8::Local<v8::Value>& jsonObject);
 private:
-    ObjectManager* m_objectManager;
-    v8::Persistent<v8::Function>* m_serializeFunc;
-
-    v8::Local<v8::Function> CreateSerializeFunc(v8::Isolate* isolate);
-    void ConvertCallback(const v8::FunctionCallbackInfo<v8::Value>& info);
+    static v8::Local<v8::Function> CreateSerializeFunc(v8::Local<v8::Context> context);
     static void ConvertCallbackStatic(const v8::FunctionCallbackInfo<v8::Value>& info);
 };
 
diff --git a/test-app/runtime/src/main/cpp/MetadataNode.cpp b/test-app/runtime/src/main/cpp/MetadataNode.cpp
index 552931183..6fe1bbc1f 100644
--- a/test-app/runtime/src/main/cpp/MetadataNode.cpp
+++ b/test-app/runtime/src/main/cpp/MetadataNode.cpp
@@ -13,6 +13,7 @@
 #include <cctype>
 #include <dirent.h>
 #include "ManualInstrumentation.h"
+#include "JSONObjectHelper.h"
 
 #include "v8.h"
 
@@ -1367,6 +1368,10 @@ void MetadataNode::PackageGetterCallback(Local<Name> property, const PropertyCal
                 }
 
                 V8SetPrivateValue(isolate, thiz, strProperty, cachedItem);
+
+                if (node->m_name == "org/json" && child.name == "JSONObject") {
+                    JSONObjectHelper::RegisterFromFunction(isolate, cachedItem);
+                }
             }
         }
 
diff --git a/test-app/runtime/src/main/cpp/ModuleInternal.cpp b/test-app/runtime/src/main/cpp/ModuleInternal.cpp
index fc2465999..4197eb82e 100644
--- a/test-app/runtime/src/main/cpp/ModuleInternal.cpp
+++ b/test-app/runtime/src/main/cpp/ModuleInternal.cpp
@@ -22,6 +22,7 @@
 #include <mutex>
 #include <libgen.h>
 #include <dlfcn.h>
+#include <sys/stat.h>
 
 using namespace v8;
 using namespace std;
@@ -31,6 +32,15 @@ ModuleInternal::ModuleInternal()
     : m_isolate(nullptr), m_requireFunction(nullptr), m_requireFactoryFunction(nullptr) {
 }
 
+ModuleInternal::~ModuleInternal() {
+    delete this->m_requireFunction;
+    delete this->m_requireFactoryFunction;
+    for (const auto pair: this->m_requireCache) {
+        delete pair.second;
+    }
+    this->m_requireCache.clear();
+}
+
 void ModuleInternal::Init(Isolate* isolate, const string& baseDir) {
     JEnv env;
 
@@ -451,6 +461,19 @@ ScriptCompiler::CachedData* ModuleInternal::TryLoadScriptCache(const std::string
     }
 
     auto cachePath = path + ".cache";
+
+    struct stat result;
+    if (stat(cachePath.c_str(), &result) == 0) {
+        auto cacheLastModifiedTime = result.st_mtime;
+        if (stat(path.c_str(), &result) == 0) {
+            auto jsLastModifiedTime = result.st_mtime;
+            if (jsLastModifiedTime > 0 && cacheLastModifiedTime > 0 && jsLastModifiedTime > cacheLastModifiedTime) {
+                // The javascript file is more recent than the cache file => ignore the cache
+                return nullptr;
+            }
+        }
+    }
+
     int length = 0;
     auto data = File::ReadBinary(cachePath, length);
     if (!data) {
diff --git a/test-app/runtime/src/main/cpp/ModuleInternal.h b/test-app/runtime/src/main/cpp/ModuleInternal.h
index 7d7b8d06c..9ba79cc78 100644
--- a/test-app/runtime/src/main/cpp/ModuleInternal.h
+++ b/test-app/runtime/src/main/cpp/ModuleInternal.h
@@ -19,6 +19,8 @@ class ModuleInternal {
     public:
         ModuleInternal();
 
+        ~ModuleInternal();
+
         void Init(v8::Isolate* isolate, const std::string& baseDir = "");
 
         void Load(const std::string& path);
diff --git a/test-app/runtime/src/main/cpp/Runtime.cpp b/test-app/runtime/src/main/cpp/Runtime.cpp
index 897664d69..6ea451d22 100644
--- a/test-app/runtime/src/main/cpp/Runtime.cpp
+++ b/test-app/runtime/src/main/cpp/Runtime.cpp
@@ -203,6 +203,12 @@ void Runtime::Init(jstring filesPath, jstring nativeLibDir, bool verboseLoggingE
     m_isolate = PrepareV8Runtime(filesRoot, nativeLibDirStr, packageNameStr, isDebuggable, callingDirStr, profilerOutputDirStr, maxLogcatObjectSize, forceLog);
 }
 
+Runtime::~Runtime() {
+    delete this->m_objectManager;
+    delete this->m_heapSnapshotBlob;
+    delete this->m_startupData;
+}
+
 std::string Runtime::ReadFileText(const std::string& filePath) {
 #ifdef APPLICATION_IN_DEBUG
     std::lock_guard<std::mutex> lock(m_fileWriteMutex);
@@ -717,7 +723,6 @@ Isolate* Runtime::PrepareV8Runtime(const string& filesPath, const string& native
     ArrayHelper::Init(context);
 
     m_arrayBufferHelper.CreateConvertFunctions(isolate, global, m_objectManager);
-    m_jsonObjectHelper.CreateConvertFunctions(isolate, global, m_objectManager);
 
     s_mainThreadInitialized = true;
 
diff --git a/test-app/runtime/src/main/cpp/Runtime.h b/test-app/runtime/src/main/cpp/Runtime.h
index a0463db89..60fac1f2d 100644
--- a/test-app/runtime/src/main/cpp/Runtime.h
+++ b/test-app/runtime/src/main/cpp/Runtime.h
@@ -7,7 +7,6 @@
 #include "SimpleAllocator.h"
 #include "WeakRef.h"
 #include "ArrayBufferHelper.h"
-#include "JSONObjectHelper.h"
 #include "Profiler.h"
 #include "ModuleInternal.h"
 #include "File.h"
@@ -23,6 +22,8 @@ class Runtime {
             CONSTANTS = 1
         };
 
+        ~Runtime();
+
         static Runtime* GetRuntime(int runtimeId);
 
         static Runtime* GetRuntime(v8::Isolate* isolate);
@@ -78,7 +79,6 @@ class Runtime {
         ModuleInternal m_module;
 
         ArrayBufferHelper m_arrayBufferHelper;
-        JSONObjectHelper m_jsonObjectHelper;
 
         WeakRef m_weakRef;
 
diff --git a/test-app/runtime/src/main/cpp/com_tns_Runtime.cpp b/test-app/runtime/src/main/cpp/com_tns_Runtime.cpp
index 11eed26c0..e1fb36953 100644
--- a/test-app/runtime/src/main/cpp/com_tns_Runtime.cpp
+++ b/test-app/runtime/src/main/cpp/com_tns_Runtime.cpp
@@ -322,12 +322,18 @@ extern "C" JNIEXPORT void Java_com_tns_Runtime_TerminateWorkerCallback(JNIEnv* e
 
     auto isolate = runtime->GetIsolate();
 
-    v8::Isolate::Scope isolate_scope(isolate);
-    v8::HandleScope handleScope(isolate);
+    {
+        v8::Isolate::Scope isolate_scope(isolate);
+        v8::HandleScope handleScope(isolate);
+
+        CallbackHandlers::TerminateWorkerThread(isolate);
+
+        runtime->DestroyRuntime();
+    }
 
-    CallbackHandlers::TerminateWorkerThread(isolate);
+    isolate->Dispose();
 
-    runtime->DestroyRuntime();
+    delete runtime;
 }
 
 extern "C" JNIEXPORT void Java_com_tns_Runtime_ClearWorkerPersistent(JNIEnv* env, jobject obj, jint runtimeId, jint workerId) {
diff --git a/v8-versions.json b/v8-versions.json
index dafefdd47..6f49d02a2 100644
--- a/v8-versions.json
+++ b/v8-versions.json
@@ -1,5 +1,5 @@
 {
-    ">=6.2.9 <6.4.0": "7.8.279.19",
+    ">=6.2.9 <6.5.0": "7.8.279.19",
     ">=6.1.9 <6.3.0": "7.7.299.11",
     ">=6.0.9 <6.2.0": "7.6.303.28",
     ">=5.9.9 <6.0.9": "7.5.288.22",