diff --git a/netty-mqtt/src/main/java/org/thingsboard/mqtt/MqttChannelHandler.java b/netty-mqtt/src/main/java/org/thingsboard/mqtt/MqttChannelHandler.java
index c927c428e6..d2a1ad129e 100644
--- a/netty-mqtt/src/main/java/org/thingsboard/mqtt/MqttChannelHandler.java
+++ b/netty-mqtt/src/main/java/org/thingsboard/mqtt/MqttChannelHandler.java
@@ -222,6 +222,9 @@ final class MqttChannelHandler extends SimpleChannelInboundHandler<MqttMessage>
 
     private void handlePuback(MqttPubAckMessage message) {
         MqttPendingPublish pendingPublish = this.client.getPendingPublishes().get(message.variableHeader().messageId());
+        if (pendingPublish == null) {
+            return;
+        }
         pendingPublish.getFuture().setSuccess(null);
         pendingPublish.onPubackReceived();
         this.client.getPendingPublishes().remove(message.variableHeader().messageId());
diff --git a/ui/src/app/extension/extensions-forms/extension-form-mqtt.tpl.html b/ui/src/app/extension/extensions-forms/extension-form-mqtt.tpl.html
index 9f0b547eef..6c0ab90e47 100644
--- a/ui/src/app/extension/extensions-forms/extension-form-mqtt.tpl.html
+++ b/ui/src/app/extension/extensions-forms/extension-form-mqtt.tpl.html
@@ -261,7 +261,7 @@
                                                                                 </md-input-container>
                                                                                 <md-input-container flex="60" class="md-block" md-is-error="theForm['mqttFilterExpression' + brokerIndex + mapIndex].$touched && theForm['mqttFilterExpression' + brokerIndex + mapIndex].$invalid">
                                                                                     <label translate>extension.filter-expression</label>
-                                                                                    <input required name="mqttFilterExpression{{brokerIndex}}{{mapIndex}}" ng-model="map.converter.filterExpression">
+                                                                                    <input name="mqttFilterExpression{{brokerIndex}}{{mapIndex}}" ng-model="map.converter.filterExpression">
                                                                                     <div ng-messages="theForm['mqttFilterExpression' + brokerIndex + mapIndex].$error">
                                                                                         <div translate ng-message="required">extension.field-required</div>
                                                                                     </div>