diff --git a/hapi-fhir-base/src/main/java/ca/uhn/fhir/i18n/Msg.java b/hapi-fhir-base/src/main/java/ca/uhn/fhir/i18n/Msg.java
index 1add165c850..b63efa141b5 100644
--- a/hapi-fhir-base/src/main/java/ca/uhn/fhir/i18n/Msg.java
+++ b/hapi-fhir-base/src/main/java/ca/uhn/fhir/i18n/Msg.java
@@ -25,7 +25,7 @@ public final class Msg {
 
 	/**
 	 * IMPORTANT: Please update the following comment after you add a new code
-	 * Last code value: 2084
+	 * Last code value: 2086
 	 */
 
 	private Msg() {}
diff --git a/hapi-fhir-docs/src/main/resources/ca/uhn/hapi/fhir/changelog/6_1_0/3684-subscription-for-delivering-delete-events-formatted-wrong.yaml b/hapi-fhir-docs/src/main/resources/ca/uhn/hapi/fhir/changelog/6_1_0/3684-subscription-for-delivering-delete-events-formatted-wrong.yaml
new file mode 100644
index 00000000000..0072293d31a
--- /dev/null
+++ b/hapi-fhir-docs/src/main/resources/ca/uhn/hapi/fhir/changelog/6_1_0/3684-subscription-for-delivering-delete-events-formatted-wrong.yaml
@@ -0,0 +1,6 @@
+---
+type: fix
+issue: 3684
+jira: SMILE-4398
+title: "Moved the `http://hapifhir.io/fhir/StructureDefinition/subscription-send-delete-messages` from the Subscription
+to the Subscription's Channel element."
diff --git a/hapi-fhir-jpaserver-test-utilities/src/test/java/ca/uhn/fhir/jpa/subscription/BaseSubscriptionsR4Test.java b/hapi-fhir-jpaserver-test-utilities/src/test/java/ca/uhn/fhir/jpa/subscription/BaseSubscriptionsR4Test.java
index f4febcf4d2a..fa459992dad 100644
--- a/hapi-fhir-jpaserver-test-utilities/src/test/java/ca/uhn/fhir/jpa/subscription/BaseSubscriptionsR4Test.java
+++ b/hapi-fhir-jpaserver-test-utilities/src/test/java/ca/uhn/fhir/jpa/subscription/BaseSubscriptionsR4Test.java
@@ -117,7 +117,7 @@ public abstract class BaseSubscriptionsR4Test extends BaseResourceProviderR4Test
 	protected Subscription createSubscription(String theCriteria, String thePayload, Extension theExtension) {
 		Subscription subscription = newSubscription(theCriteria, thePayload);
 		if (theExtension != null) {
-			subscription.getExtension().add(theExtension);
+			subscription.getChannel().addExtension(theExtension);
 		}
 
 		MethodOutcome methodOutcome = myClient.create().resource(subscription).execute();
diff --git a/hapi-fhir-storage/src/main/java/ca/uhn/fhir/jpa/subscription/match/registry/SubscriptionCanonicalizer.java b/hapi-fhir-storage/src/main/java/ca/uhn/fhir/jpa/subscription/match/registry/SubscriptionCanonicalizer.java
index a4272389b52..9ba454786ac 100644
--- a/hapi-fhir-storage/src/main/java/ca/uhn/fhir/jpa/subscription/match/registry/SubscriptionCanonicalizer.java
+++ b/hapi-fhir-storage/src/main/java/ca/uhn/fhir/jpa/subscription/match/registry/SubscriptionCanonicalizer.java
@@ -275,7 +275,7 @@ public class SubscriptionCanonicalizer {
 			}
 		}
 
-		Extension extension = subscription.getExtensionByUrl(EX_SEND_DELETE_MESSAGES);
+		Extension extension = subscription.getChannel().getExtensionByUrl(EX_SEND_DELETE_MESSAGES);
 		if (extension != null && extension.hasValue() && extension.getValue() instanceof BooleanType) {
 			retVal.setSendDeleteMessages(((BooleanType) extension.getValue()).booleanValue());
 		}
diff --git a/hapi-fhir-storage/src/test/java/ca/uhn/fhir/jpa/subscription/match/registry/SubscriptionCanonicalizerTest.java b/hapi-fhir-storage/src/test/java/ca/uhn/fhir/jpa/subscription/match/registry/SubscriptionCanonicalizerTest.java
index 91867393809..b6d42439693 100644
--- a/hapi-fhir-storage/src/test/java/ca/uhn/fhir/jpa/subscription/match/registry/SubscriptionCanonicalizerTest.java
+++ b/hapi-fhir-storage/src/test/java/ca/uhn/fhir/jpa/subscription/match/registry/SubscriptionCanonicalizerTest.java
@@ -33,7 +33,7 @@ class SubscriptionCanonicalizerTest {
 		Extension sendDeleteMessagesExtension = new Extension()
 			.setUrl(EX_SEND_DELETE_MESSAGES)
 			.setValue(new BooleanType(true));
-		subscription.getExtension().add(sendDeleteMessagesExtension);
+		subscription.getChannel().addExtension(sendDeleteMessagesExtension);
 
 		CanonicalSubscription canonicalSubscription = testedSC.canonicalize(subscription);