diff --git a/pkg/apis/messaging/v1/subscription_defaults.go b/pkg/apis/messaging/v1/subscription_defaults.go
index c2ddc46ac0d..6cdf2bab9b5 100644
--- a/pkg/apis/messaging/v1/subscription_defaults.go
+++ b/pkg/apis/messaging/v1/subscription_defaults.go
@@ -25,5 +25,9 @@ func (s *Subscription) SetDefaults(ctx context.Context) {
 }
 
 func (ss *SubscriptionSpec) SetDefaults(ctx context.Context) {
-	// TODO anything?
+	// HACK if a channel ref is a kafka channel ref, we need to hack it around to use only v1beta1
+	//  TODO(slinkydeveloper) REMOVE AFTER 0.22 release
+	if ss.Channel.Kind == "KafkaChannel" && ss.Channel.APIVersion == "messaging.knative.dev/v1alpha1" {
+		ss.Channel.APIVersion = "messaging.knative.dev/v1beta1"
+	}
 }
diff --git a/pkg/apis/messaging/v1/subscription_validation.go b/pkg/apis/messaging/v1/subscription_validation.go
index f2496bc7afa..e3f3a517290 100644
--- a/pkg/apis/messaging/v1/subscription_validation.go
+++ b/pkg/apis/messaging/v1/subscription_validation.go
@@ -80,8 +80,16 @@ func (s *Subscription) CheckImmutableFields(ctx context.Context, original *Subsc
 		return nil
 	}
 
+	// TODO(slinkydeveloper)
+	//  HACK around the immutability check to make sure the update script can upgrade the api version
+	//  REMOVE AFTER 0.22 release
+	ignoredFields := []string{"Subscriber", "Reply"}
+	if original.Spec.Channel.Kind == "KafkaChannel" && original.Spec.Channel.APIVersion == "messaging.knative.dev/v1alpha1" && s.Spec.Channel.APIVersion == "messaging.knative.dev/v1beta1" {
+		ignoredFields = append(ignoredFields, "Channel.APIVersion")
+	}
+
 	// Only Subscriber and Reply are mutable.
-	ignoreArguments := cmpopts.IgnoreFields(SubscriptionSpec{}, "Subscriber", "Reply")
+	ignoreArguments := cmpopts.IgnoreFields(SubscriptionSpec{}, ignoredFields...)
 	if diff, err := kmp.ShortDiff(original.Spec, s.Spec, ignoreArguments); err != nil {
 		return &apis.FieldError{
 			Message: "Failed to diff Subscription",
diff --git a/pkg/apis/messaging/v1/subscription_validation_test.go b/pkg/apis/messaging/v1/subscription_validation_test.go
index e31086eba62..b956b8215ae 100644
--- a/pkg/apis/messaging/v1/subscription_validation_test.go
+++ b/pkg/apis/messaging/v1/subscription_validation_test.go
@@ -329,6 +329,29 @@ func TestSubscriptionImmutable(t *testing.T) {
 			},
 		},
 		want: nil,
+	}, {
+		name: "valid, kafkachannel hack",
+		c: &Subscription{
+			Spec: SubscriptionSpec{
+				Channel: corev1.ObjectReference{
+					Name:       channelName,
+					Kind:       "KafkaChannel",
+					APIVersion: "messaging.knative.dev/v1beta1",
+				},
+				Subscriber: getValidDestination(),
+			},
+		},
+		og: &Subscription{
+			Spec: SubscriptionSpec{
+				Channel: corev1.ObjectReference{
+					Name:       channelName,
+					Kind:       "KafkaChannel",
+					APIVersion: "messaging.knative.dev/v1alpha1",
+				},
+				Subscriber: getValidDestination(),
+			},
+		},
+		want: nil,
 	}, {
 		name: "Channel changed",
 		c: &Subscription{
diff --git a/pkg/apis/messaging/v1beta1/subscription_defaults.go b/pkg/apis/messaging/v1beta1/subscription_defaults.go
index 16fd42ea588..6694bb17a45 100644
--- a/pkg/apis/messaging/v1beta1/subscription_defaults.go
+++ b/pkg/apis/messaging/v1beta1/subscription_defaults.go
@@ -25,5 +25,9 @@ func (s *Subscription) SetDefaults(ctx context.Context) {
 }
 
 func (ss *SubscriptionSpec) SetDefaults(ctx context.Context) {
-	// TODO anything?
+	// HACK if a channel ref is a kafka channel ref, we need to hack it around to use only v1beta1
+	//  TODO(slinkydeveloper) REMOVE AFTER 0.22 release
+	if ss.Channel.Kind == "KafkaChannel" && ss.Channel.APIVersion == "messaging.knative.dev/v1alpha1" {
+		ss.Channel.APIVersion = "messaging.knative.dev/v1beta1"
+	}
 }
diff --git a/pkg/apis/messaging/v1beta1/subscription_validation.go b/pkg/apis/messaging/v1beta1/subscription_validation.go
index 5cf8c2e8515..6d316efbb70 100644
--- a/pkg/apis/messaging/v1beta1/subscription_validation.go
+++ b/pkg/apis/messaging/v1beta1/subscription_validation.go
@@ -75,8 +75,16 @@ func (s *Subscription) CheckImmutableFields(ctx context.Context, original *Subsc
 		return nil
 	}
 
+	// TODO(slinkydeveloper)
+	//  HACK around the immutability check to make sure the update script can upgrade the api version
+	//  REMOVE AFTER 0.22 release
+	ignoredFields := []string{"Subscriber", "Reply"}
+	if original.Spec.Channel.Kind == "KafkaChannel" && original.Spec.Channel.APIVersion == "messaging.knative.dev/v1alpha1" && s.Spec.Channel.APIVersion == "messaging.knative.dev/v1beta1" {
+		ignoredFields = append(ignoredFields, "Channel.APIVersion")
+	}
+
 	// Only Subscriber and Reply are mutable.
-	ignoreArguments := cmpopts.IgnoreFields(SubscriptionSpec{}, "Subscriber", "Reply")
+	ignoreArguments := cmpopts.IgnoreFields(SubscriptionSpec{}, ignoredFields...)
 	if diff, err := kmp.ShortDiff(original.Spec, s.Spec, ignoreArguments); err != nil {
 		return &apis.FieldError{
 			Message: "Failed to diff Subscription",
diff --git a/pkg/apis/messaging/v1beta1/subscription_validation_test.go b/pkg/apis/messaging/v1beta1/subscription_validation_test.go
index c9a1a9efcdc..71e20fa4495 100644
--- a/pkg/apis/messaging/v1beta1/subscription_validation_test.go
+++ b/pkg/apis/messaging/v1beta1/subscription_validation_test.go
@@ -282,6 +282,29 @@ func TestSubscriptionImmutable(t *testing.T) {
 			},
 		},
 		want: nil,
+	}, {
+		name: "valid, kafkachannel hack",
+		c: &Subscription{
+			Spec: SubscriptionSpec{
+				Channel: corev1.ObjectReference{
+					Name:       channelName,
+					Kind:       "KafkaChannel",
+					APIVersion: "messaging.knative.dev/v1beta1",
+				},
+				Subscriber: getValidDestination(),
+			},
+		},
+		og: &Subscription{
+			Spec: SubscriptionSpec{
+				Channel: corev1.ObjectReference{
+					Name:       channelName,
+					Kind:       "KafkaChannel",
+					APIVersion: "messaging.knative.dev/v1alpha1",
+				},
+				Subscriber: getValidDestination(),
+			},
+		},
+		want: nil,
 	}, {
 		name: "valid, new Reply",
 		c: &Subscription{