diff --git a/lib/browser/mqtt_request_response/protocol_adapter.ts b/lib/browser/mqtt_request_response/protocol_adapter.ts
index 06d409af..8ca06643 100644
--- a/lib/browser/mqtt_request_response/protocol_adapter.ts
+++ b/lib/browser/mqtt_request_response/protocol_adapter.ts
@@ -461,8 +461,8 @@ export class ProtocolClientAdapter extends BufferedEventEmitter {
 
     private static isUnsubackReasonCodeRetryable(reasonCode: mqtt5.UnsubackReasonCode) : boolean {
         switch (reasonCode) {
-            case mqtt5.UnsubackReasonCode.UnspecifiedError:
             case mqtt5.UnsubackReasonCode.ImplementationSpecificError:
+            case mqtt5.UnsubackReasonCode.PacketIdentifierInUse:
                 return true;
 
             default:
@@ -472,7 +472,6 @@ export class ProtocolClientAdapter extends BufferedEventEmitter {
 
     private static isSubackReasonCodeRetryable(reasonCode: mqtt5.SubackReasonCode) : boolean {
         switch (reasonCode) {
-            case mqtt5.SubackReasonCode.UnspecifiedError:
             case mqtt5.SubackReasonCode.PacketIdentifierInUse:
             case mqtt5.SubackReasonCode.ImplementationSpecificError:
             case mqtt5.SubackReasonCode.QuotaExceeded:
diff --git a/lib/browser/mqtt_request_response/subscription_manager.ts b/lib/browser/mqtt_request_response/subscription_manager.ts
index 673287cb..2c5f0b6c 100644
--- a/lib/browser/mqtt_request_response/subscription_manager.ts
+++ b/lib/browser/mqtt_request_response/subscription_manager.ts
@@ -529,7 +529,7 @@ export class SubscriptionManager extends BufferedEventEmitter {
             record.status = SubscriptionStatus.Subscribed;
             this.emitEvents(record, SubscriptionEventType.StreamingSubscriptionEstablished);
         } else {
-            if (event.retryable) {
+            if (event.retryable && !this.closed) {
                 this.activateSubscription(record);
             } else {
                 record.poisoned = true;