diff --git a/hapi-fhir-jpaserver-base/src/main/java/ca/uhn/fhir/jpa/interceptor/RestHookSubscriptionDstu2Interceptor.java b/hapi-fhir-jpaserver-base/src/main/java/ca/uhn/fhir/jpa/interceptor/RestHookSubscriptionDstu2Interceptor.java
index c74fb12602f..bfb5d778c94 100644
--- a/hapi-fhir-jpaserver-base/src/main/java/ca/uhn/fhir/jpa/interceptor/RestHookSubscriptionDstu2Interceptor.java
+++ b/hapi-fhir-jpaserver-base/src/main/java/ca/uhn/fhir/jpa/interceptor/RestHookSubscriptionDstu2Interceptor.java
@@ -83,7 +83,12 @@ public class RestHookSubscriptionDstu2Interceptor extends BaseRestHookSubscripti
 	 * @param theOperation
 	 */
 	private void checkSubscriptions(IIdType idType, String resourceType, RestOperationTypeEnum theOperation) {
-		for (Subscription subscription : myRestHookSubscriptions) {
+		//avoid a ConcurrentModificationException by copying to an array
+		for (Object object : myRestHookSubscriptions.toArray()) {
+			if (object == null) {
+				continue;
+			}
+			Subscription subscription = (Subscription) object;
 			// see if the criteria matches the created object
 			ourLog.info("Checking subscription {} for {} with criteria {}", subscription.getIdElement().getIdPart(), resourceType, subscription.getCriteria());
 
@@ -121,6 +126,8 @@ public class RestHookSubscriptionDstu2Interceptor extends BaseRestHookSubscripti
 		}
 	}
 
+
+
 	/**
 	 * Creates an HTTP Post for a subscription
 	 */
diff --git a/hapi-fhir-jpaserver-base/src/main/java/ca/uhn/fhir/jpa/interceptor/RestHookSubscriptionDstu3Interceptor.java b/hapi-fhir-jpaserver-base/src/main/java/ca/uhn/fhir/jpa/interceptor/RestHookSubscriptionDstu3Interceptor.java
index 0eda2bd28a2..ad53b7b8a67 100644
--- a/hapi-fhir-jpaserver-base/src/main/java/ca/uhn/fhir/jpa/interceptor/RestHookSubscriptionDstu3Interceptor.java
+++ b/hapi-fhir-jpaserver-base/src/main/java/ca/uhn/fhir/jpa/interceptor/RestHookSubscriptionDstu3Interceptor.java
@@ -82,7 +82,13 @@ public class RestHookSubscriptionDstu3Interceptor extends BaseRestHookSubscripti
 	 * @param theOperation
 	 */
 	private void checkSubscriptions(IIdType idType, String resourceType, RestOperationTypeEnum theOperation) {
-		for (Subscription subscription : myRestHookSubscriptions) {
+		//avoid a ConcurrentModificationException by copying to an array
+		for (Object object : myRestHookSubscriptions.toArray()) {
+		//for (Subscription subscription : myRestHookSubscriptions) {
+			if (object == null) {
+				continue;
+			}
+			Subscription subscription = (Subscription) object;
 			// see if the criteria matches the created object
 			ourLog.info("Checking subscription {} for {} with criteria {}", subscription.getIdElement().getIdPart(), resourceType, subscription.getCriteria());