diff --git a/lib/api/GwApi.h b/lib/api/GwApi.h
index cb54cc3..af3b010 100644
--- a/lib/api/GwApi.h
+++ b/lib/api/GwApi.h
@@ -61,6 +61,7 @@ class GwApi{
         protected:
             virtual bool iset(const String &file, const String &name, Ptr v) = 0;
             virtual Ptr iget(const String &name, int &result) = 0;
+            virtual bool iclaim(const String &name, const String &task)=0;
         public:
             template <typename T>
             bool set(const T &v){
@@ -71,6 +72,10 @@ class GwApi{
                 res=-1;
                 return T();
             }
+            template <typename T>
+            bool claim(const String &task){
+                return false;
+            }
         };
         class Status{
             public:
@@ -248,7 +253,12 @@ class GwApi{
         }\
         type *tp=(type*)ptr.get(); \
         return type(*tp); \
-    }
+    }\
+    template<> \
+    inline bool GwApi::TaskInterfaces::claim<type>(const String &task) {\
+        return iclaim(#type,task);\
+    }\
+
 #ifndef DECLARE_TASKIF
     #define DECLARE_TASKIF(type) DECLARE_TASKIF_IMPL(type)
 #endif
diff --git a/lib/buttontask/GwButtonTask.cpp b/lib/buttontask/GwButtonTask.cpp
index 9ea4beb..72b84cf 100644
--- a/lib/buttontask/GwButtonTask.cpp
+++ b/lib/buttontask/GwButtonTask.cpp
@@ -110,4 +110,14 @@ void handleButtons(GwApi *api){
     }
     vTaskDelete(NULL);
     #endif
+}
+
+void initButtons(GwApi *api){
+    #ifndef GWBUTTON_PIN
+    api->getLogger()->logDebug(GwLog::LOG,"no buttons defined, no button task");
+    return;
+    #endif
+    const String taskname("buttonTask");
+    api->addUserTask(handleButtons,taskname);
+    api->taskInterfaces()->claim<IButtonTask>(taskname);
 }
\ No newline at end of file
diff --git a/lib/buttontask/GwButtonTask.h b/lib/buttontask/GwButtonTask.h
index 76a3301..853e6c6 100644
--- a/lib/buttontask/GwButtonTask.h
+++ b/lib/buttontask/GwButtonTask.h
@@ -2,6 +2,6 @@
 #define _GWBUTTONTASK_H
 #include "GwApi.h"
 //task function
-void handleButtons(GwApi *param);
-DECLARE_USERTASK(handleButtons);
+void initButtons(GwApi *param);
+DECLARE_INITFUNCTION(initButtons);
 #endif
\ No newline at end of file
diff --git a/lib/usercode/GwUserCode.cpp b/lib/usercode/GwUserCode.cpp
index 189ebcd..0473910 100644
--- a/lib/usercode/GwUserCode.cpp
+++ b/lib/usercode/GwUserCode.cpp
@@ -124,6 +124,7 @@ class TaskInterfacesStorage{
             }
             if (it->second.task != task){
                 LOG_DEBUG(GwLog::ERROR,"TaskInterfaces: invalid set %s wrong task, expected %s , got %s",name.c_str(),it->second.task.c_str(),task.c_str());
+                return false;
             }
             auto vit=values.find(name);
             if (vit != values.end()){
@@ -150,15 +151,32 @@ class TaskInterfacesStorage{
 class TaskInterfacesImpl : public GwApi::TaskInterfaces{
     String task;
     TaskInterfacesStorage *storage;
+    GwLog *logger;
+    bool isInit=false;
     public:
-        TaskInterfacesImpl(const String &n,TaskInterfacesStorage *s):
-            task(n),storage(s){}
+        TaskInterfacesImpl(const String &n,TaskInterfacesStorage *s, GwLog *l,bool i):
+            task(n),storage(s),isInit(i),logger(l){}
         virtual bool iset(const String &file, const String &name, Ptr v){
             return storage->set(file,name,task,v);
         }
         virtual Ptr iget(const String &name, int &result){
             return storage->get(name,result);
         }
+        virtual bool iclaim(const String &name, const String &task){
+            if (! isInit) return false;
+            auto it=registrations().find(name);
+            if (it == registrations().end()){
+                LOG_DEBUG(GwLog::ERROR,"unable to claim interface %s for task %s, not registered",name.c_str(),task.c_str());
+                return false;
+            }
+            if (!it->second.task.isEmpty()){
+                LOG_DEBUG(GwLog::ERROR,"unable to claim interface %s for task %s, already claimed by %s",name.c_str(),task.c_str(),it->second.task.c_str());
+                return false;
+            }
+            it->second.task=task;
+            LOG_DEBUG(GwLog::LOG,"claimed interface %s for task %s",name.c_str(),task.c_str());
+            return true;
+        }
 };
 
 
@@ -187,7 +205,7 @@ public:
         this->mainLock=mainLock;
         this->name=name;
         localLock=xSemaphoreCreateMutex();
-        interfaces=new TaskInterfacesImpl(name,s);
+        interfaces=new TaskInterfacesImpl(name,s,api->getLogger(),init);
         isInit=init;
     }
     virtual GwRequestQueue *getQueue()