diff --git a/src/Adapter.hxx b/src/Adapter.hxx
index 5e3e010..e0e784b 100644
--- a/src/Adapter.hxx
+++ b/src/Adapter.hxx
@@ -16,12 +16,6 @@ namespace pEp {
 
         extern std::thread _sync_thread;
         extern ::utility::locked_queue<::SYNC_EVENT, ::free_Sync_event> sync_evt_q;
-        extern std::mutex mut;
-
-        ::SYNC_EVENT _retrieve_next_sync_event(void *management, unsigned threshold);
-
-        static std::exception_ptr _ex;
-        static std::atomic_bool register_done{false};
 
         /*
          * Sync Thread
@@ -34,10 +28,9 @@ namespace pEp {
          */
         // private
         template<class T>
-        void sync_thread(Session *rhs, T *obj, function<void(T *)> _startup, function<void(T *)> _shutdown)
+        void sync_thread(T *obj, function<void(T *)> _startup, function<void(T *)> _shutdown)
         {
             pEpLog("called");
-            _ex = nullptr;
 
             // 1. Execute registered startup function
             if (obj && _startup) {
@@ -46,28 +39,10 @@ namespace pEp {
 
             // 2. Create session for the sync thread
             pEpLog("creating session for the sync thread");
-            session.initialize(
-                rhs->_sync_mode,
-                rhs->_adapter_manages_sync_thread,
-                rhs->_messageToSend,
-                rhs->_notifyHandshake);
-
-            try {
-                // 3. register_sync_callbacks()
-                ::PEP_STATUS status = ::register_sync_callbacks(
-                    session(),
-                    nullptr,
-                    session._notifyHandshake,
-                    _retrieve_next_sync_event);
-                throw_status(status);
-
-                register_done.store(true);
-            } catch (...) {
-                _ex = std::current_exception();
-                register_done.store(true);
-                return;
-            }
+            session();
 
+            // 3. Enter Sync Event Processing Loop (do_sync_protocol())
+            // this internally calls _retrieve_next_sync_event
             pEpLog("sync protocol loop started");
             ::do_sync_protocol(session(), (void *)obj);
             pEpLog("sync protocol loop ended");
@@ -90,26 +65,10 @@ namespace pEp {
         void startup(T *obj, std::function<void(T *)> _startup, std::function<void(T *)> _shutdown)
         {
             pEpLog("called");
-            // refresh the session
-            // due to partially initialized session, see session.initialize()
-            session.refresh();
-
             if (!_sync_thread.joinable()) {
-                register_done.store(false);
-                pEpLog("creating sync-thread");
-                // 2. Start the sync thread
-                _sync_thread = std::thread(sync_thread<T>, &session, obj, _startup, _shutdown);
-                // 3. Defer execution until sync thread register_sync_callbacks() has returned
-                while (register_done.load() == false) {
-                    pEpLog("waiting for sync-thread to init...");
-                    std::this_thread::sleep_for(std::chrono::milliseconds(100));
-                }
-
-                // 4. Throw pending exception from the sync thread
-                if (_ex) {
-                    pEpLog("exception pending, rethrowing");
-                    std::rethrow_exception(_ex);
-                }
+                _sync_thread = std::thread(sync_thread<T>, obj, _startup, _shutdown);
+            } else {
+                pEpLog("Sync thread already running");
             }
         }
     } // namespace Adapter