diff --git a/src/daemon.vala b/src/daemon.vala
index 55d70b8..4f7871e 100644
--- a/src/daemon.vala
+++ b/src/daemon.vala
@@ -82,12 +82,17 @@ namespace Pamac {
 		public Mutex provider_mutex;
 		public int? choosen_provider;
 		private bool force_refresh;
+		private bool enable_downgrade;
+		private Alpm.TransFlag flags;
+		private string[] to_install;
+		private string[] to_remove;
+		private string[] to_load;
+		private string[] temporary_ignorepkgs;
 		private ThreadPool<AlpmAction> thread_pool;
 		private Mutex databases_lock_mutex;
 		private Json.Array aur_updates_results;
 		private HashTable<string, Json.Array> aur_search_results;
 		private HashTable<string, Json.Object> aur_infos;
-		private bool intern_lock;
 		private bool extern_lock;
 		private GLib.File lockfile;
 		private ErrorInfos current_error;
@@ -122,7 +127,6 @@ namespace Pamac {
 			aur_search_results = new HashTable<string, Json.Array> (str_hash, str_equal);
 			aur_infos = new HashTable<string, Json.Object> (str_hash, str_equal);
 			timer = new Timer ();
-			intern_lock = false;
 			extern_lock = false;
 			refresh_handle ();
 			Timeout.add (500, check_pacman_running);
@@ -193,8 +197,9 @@ namespace Pamac {
 				}
 			} else {
 				if (lockfile.query_exists ()) {
-					if (!intern_lock) {
+					if (databases_lock_mutex.trylock ()) {
 						extern_lock = true;
+						databases_lock_mutex.unlock ();
 					}
 				}
 			}
@@ -354,8 +359,8 @@ namespace Pamac {
 		}
 
 		private void refresh () {
+			databases_lock_mutex.lock ();
 			write_log_file ("synchronizing package lists");
-			intern_lock = true;
 			current_error = ErrorInfos ();
 			int force = (force_refresh) ? 1 : 0;
 			uint success = 0;
@@ -366,11 +371,17 @@ namespace Pamac {
 				if (cancellable.is_cancelled ()) {
 					refresh_handle ();
 					refresh_finished (false);
-					intern_lock = false;
+					databases_lock_mutex.unlock ();
 					return;
 				}
 				if (db.update (force) >= 0) {
 					success++;
+				} else {
+					Alpm.Errno errno = alpm_handle.errno ();
+					current_error.errno = (uint) errno;
+					if (errno != 0) {
+						current_error.details = { Alpm.strerror (errno) };
+					}
 				}
 				syncdbs.next ();
 			}
@@ -378,17 +389,12 @@ namespace Pamac {
 			// We should always succeed if at least one DB was upgraded - we may possibly
 			// fail later with unresolved deps, but that should be rare, and would be expected
 			if (success == 0) {
-				Alpm.Errno errno = alpm_handle.errno ();
-				current_error.errno = (uint) errno;
 				current_error.message = _("Failed to synchronize any databases");
-				if (errno != 0) {
-					current_error.details = { Alpm.strerror (errno) };
-				}
 				refresh_finished (false);
 			} else {
 				refresh_finished (true);
 			}
-			intern_lock = false;
+			databases_lock_mutex.unlock ();
 		}
 
 		public void start_refresh (bool force) {
@@ -419,12 +425,17 @@ namespace Pamac {
 			return result;
 		}
 
-		public void add_ignorepkg (string pkgname) {
-			alpm_handle.add_ignorepkg (pkgname);
+		private void add_ignorepkgs () {
+			foreach (unowned string pkgname in temporary_ignorepkgs) {
+				alpm_handle.add_ignorepkg (pkgname);
+			}
 		}
 
-		public void remove_ignorepkg (string pkgname) {
-			alpm_handle.remove_ignorepkg (pkgname);
+		private void remove_ignorepkgs () {
+			foreach (unowned string pkgname in temporary_ignorepkgs) {
+				alpm_handle.remove_ignorepkg (pkgname);
+			}
+			temporary_ignorepkgs = {};
 		}
 
 		public bool should_hold (string pkgname) {
@@ -1280,25 +1291,30 @@ namespace Pamac {
 			return aur_updates_infos;
 		}
 
-		public bool trans_init (Alpm.TransFlag transflags) {
+		private bool trans_init (Alpm.TransFlag flags) {
+			databases_lock_mutex.lock ();
 			current_error = ErrorInfos ();
 			cancellable.reset ();
-			if (alpm_handle.trans_init (transflags) == -1) {
+			if (alpm_handle.trans_init (flags) == -1) {
 				Alpm.Errno errno = alpm_handle.errno ();
 				current_error.errno = (uint) errno;
 				current_error.message = _("Failed to init transaction");
 				if (errno != 0) {
 					current_error.details = { Alpm.strerror (errno) };
 				}
+				databases_lock_mutex.unlock ();
 				return false;
-			} else {
-				intern_lock = true;
 			}
 			return true;
 		}
 
-		public bool trans_sysupgrade (bool enable_downgrade) {
+		private void sysupgrade_prepare () {
 			current_error = ErrorInfos ();
+			if (!trans_init (0)) {
+				trans_prepare_finished (false);
+				return;
+			}
+			add_ignorepkgs ();
 			if (alpm_handle.trans_sysupgrade ((enable_downgrade) ? 1 : 0) == -1) {
 				Alpm.Errno errno = alpm_handle.errno ();
 				current_error.errno = (uint) errno;
@@ -1306,9 +1322,21 @@ namespace Pamac {
 				if (errno != 0) {
 					current_error.details = { Alpm.strerror (errno) };
 				}
-				return false;
+				trans_release ();
+				trans_prepare_finished (false);
+				return;
+			}
+			trans_prepare_real ();
+		}
+
+		public void start_sysupgrade_prepare_ (bool enable_downgrade_, string[] temporary_ignorepkgs_) {
+			enable_downgrade = enable_downgrade_;
+			temporary_ignorepkgs = temporary_ignorepkgs_;
+			try {
+				thread_pool.add (new AlpmAction (sysupgrade_prepare));
+			} catch (ThreadError e) {
+				stderr.printf ("Thread Error %s\n", e.message);
 			}
-			return true;
 		}
 
 		private bool trans_add_pkg_real (Alpm.Package pkg) {
@@ -1330,7 +1358,7 @@ namespace Pamac {
 			return true;
 		}
 
-		public bool trans_add_pkg (string pkgname) {
+		private bool trans_add_pkg (string pkgname) {
 			current_error = ErrorInfos ();
 			unowned Alpm.Package? pkg = get_syncpkg (pkgname);
 			if (pkg == null) {
@@ -1387,7 +1415,7 @@ namespace Pamac {
 			}
 		}
 
-		public bool trans_load_pkg (string pkgpath) {
+		private bool trans_load_pkg (string pkgpath) {
 			current_error = ErrorInfos ();
 			Alpm.Package* pkg;
 			if (alpm_handle.load_tarball (pkgpath, 1, alpm_handle.localfilesiglevel, out pkg) == -1) {
@@ -1412,7 +1440,7 @@ namespace Pamac {
 			return true;
 		}
 
-		public bool trans_remove_pkg (string pkgname) {
+		private bool trans_remove_pkg (string pkgname) {
 			current_error = ErrorInfos ();
 			unowned Alpm.Package? pkg =  alpm_handle.localdb.get_pkg (pkgname);
 			if (pkg == null) {
@@ -1431,7 +1459,7 @@ namespace Pamac {
 			return true;
 		}
 
-		private void trans_prepare () {
+		private void trans_prepare_real () {
 			current_error = ErrorInfos ();
 			string[] details = {};
 			Alpm.List err_data;
@@ -1508,7 +1536,50 @@ namespace Pamac {
 			}
 		}
 
-		public void start_trans_prepare () {
+		private void trans_prepare () {
+			bool success = trans_init (flags);
+			if (success) {
+				foreach (unowned string name in to_install) {
+					success = trans_add_pkg (name);
+					if (!success) {
+						break;
+					}
+				}
+				if (success) {
+					foreach (unowned string name in to_remove) {
+						success = trans_remove_pkg (name);
+						if (!success) {
+							break;
+						}
+					}
+				}
+				if (success) {
+					foreach (unowned string path in to_load) {
+						success = trans_load_pkg (path);
+						if (!success) {
+							break;
+						}
+					}
+				}
+				if (success) {
+					trans_prepare_real ();
+				} else {
+					trans_release ();
+					trans_prepare_finished (false);
+				}
+			} else {
+				trans_prepare_finished (false);
+			}
+		}
+
+		public void start_trans_prepare (Alpm.TransFlag flags_,
+										string[] to_install_,
+										string[] to_remove_,
+										string[] to_load_) {
+			flags = flags_;
+			to_install = to_install_;
+			to_remove = to_remove_;
+			to_load = to_load_;
 			try {
 				thread_pool.add (new AlpmAction (trans_prepare));
 			} catch (ThreadError e) {
@@ -1664,7 +1735,8 @@ namespace Pamac {
 
 		public void trans_release () {
 			alpm_handle.trans_release ();
-			intern_lock = false;
+			remove_ignorepkgs ();
+			databases_lock_mutex.unlock ();
 		}
 
 		[DBus (no_reply = true)]
diff --git a/src/manager_window.vala b/src/manager_window.vala
index fdf2894..dc94b53 100644
--- a/src/manager_window.vala
+++ b/src/manager_window.vala
@@ -1618,6 +1618,8 @@ namespace Pamac {
 				if (success) {
 					transaction_running = true;
 					transaction.sysupgrade (false);
+				} else {
+					apply_button.sensitive = true;
 				}
 				refreshing = false;
 			} else {
diff --git a/src/transaction.vala b/src/transaction.vala
index d689d6d..2611550 100644
--- a/src/transaction.vala
+++ b/src/transaction.vala
@@ -54,15 +54,9 @@ namespace Pamac {
 		public abstract AlpmPackageDetails get_pkg_details (string pkgname) throws IOError;
 		public abstract async AURPackageDetails get_aur_details (string pkgname) throws IOError;
 		public abstract string[] get_pkg_uninstalled_optdeps (string pkgname) throws IOError;
-		public abstract void add_ignorepkg (string pkgname) throws IOError;
-		public abstract void remove_ignorepkg (string pkgname) throws IOError;
 		public abstract void start_get_updates (bool check_aur_updates) throws IOError;
-		public abstract bool trans_init (int transflags) throws IOError;
-		public abstract bool trans_sysupgrade (bool enable_downgrade) throws IOError;
-		public abstract bool trans_add_pkg (string pkgname) throws IOError;
-		public abstract bool trans_remove_pkg (string pkgname) throws IOError;
-		public abstract bool trans_load_pkg (string pkgpath) throws IOError;
-		public abstract void start_trans_prepare () throws IOError;
+		public abstract void start_sysupgrade_prepare (bool enable_downgrade, string[] temporary_ignorepkgs) throws IOError;
+		public abstract void start_trans_prepare (int transflags, string[] to_install, string[] to_remove, string[] to_load) throws IOError;
 		public abstract void choose_provider (int provider) throws IOError;
 		public abstract TransactionSummary get_transaction_summary () throws IOError;
 		public abstract void start_trans_commit () throws IOError;
@@ -144,7 +138,7 @@ namespace Pamac {
 		uint64 rates_nb;
 		Timer timer;
 		bool success;
-		StringBuilder dialog_textbuffer;
+		StringBuilder warning_textbuffer;
 
 		//dialogs
 		TransactionSumDialog transaction_sum_dialog;
@@ -217,7 +211,7 @@ namespace Pamac {
 			sysupgrade_after_trans = false;
 			timer = new Timer ();
 			success = false;
-			dialog_textbuffer = new StringBuilder ();
+			warning_textbuffer = new StringBuilder ();
 		}
 
 		public void run_history_dialog () {
@@ -338,17 +332,29 @@ namespace Pamac {
 			progress_box.progressbar.text = "";
 		}
 
+		void start_progressbar_pulse () {
+			pulse_timeout_id = Timeout.add (500, (GLib.SourceFunc) progress_box.progressbar.pulse);
+		}
+
+		void stop_progressbar_pulse () {
+			if (pulse_timeout_id != 0) {
+				Source.remove (pulse_timeout_id);
+				pulse_timeout_id = 0;
+				progress_box.progressbar.fraction = 0;
+			}
+		}
+
 		public void start_generate_mirrors_list () {
 			string action = dgettext (null, "Refreshing mirrors list") + "...";
 			reset_progress_box (action);
-			pulse_timeout_id = Timeout.add (500, (GLib.SourceFunc) progress_box.progressbar.pulse);
+			start_progressbar_pulse ();
 			important_details_outpout (false);
 			generate_mirrors_list ();
 			try {
 				daemon.start_generate_mirrors_list ();
 			} catch (IOError e) {
 				stderr.printf ("IOError: %s\n", e.message);
-				Source.remove (pulse_timeout_id);
+				stop_progressbar_pulse ();
 			}
 		}
 
@@ -657,60 +663,19 @@ namespace Pamac {
 			}
 		}
 
-		public void add_ignorepkg (string pkgname) {
-			try {
-				daemon.add_ignorepkg (pkgname);
-				//temporary_ignorepkgs.add (pkgname);
-			} catch (IOError e) {
-				stderr.printf ("IOError: %s\n", e.message);
-			}
-		}
-
-		public void remove_ignorepkg (string pkgname) {
-			try {
-				daemon.remove_ignorepkg (pkgname);
-			} catch (IOError e) {
-				stderr.printf ("IOError: %s\n", e.message);
-			}
-		}
-
-		public bool init (int flags) {
-			foreach (unowned string pkgname in temporary_ignorepkgs) {
-				add_ignorepkg (pkgname);
-			}
-			try {
-				return daemon.trans_init (flags);
-			} catch (IOError e) {
-				stderr.printf ("IOError: %s\n", e.message);
-				return false;
-			}
-		}
-
 		void sysupgrade_simple (bool enable_downgrade) {
 			progress_box.progressbar.fraction = 0;
-			success = init (0);
-			if (success) {
-				try {
-					success = daemon.trans_sysupgrade (enable_downgrade);
-				} catch (IOError e) {
-					stderr.printf ("IOError: %s\n", e.message);
-					success = false;
-				}
-				if (success) {
-					try {
-						daemon.start_trans_prepare ();
-					} catch (IOError e) {
-						stderr.printf ("IOError: %s\n", e.message);
-						release ();
-						success = false;
-						finish_transaction ();
-					}
-				} else {
-					release ();
-					handle_error (get_current_error ());
-				}
-			} else {
-				handle_error (get_current_error ());
+			string[] temporary_ignorepkgs_ = {};
+			foreach (unowned string pkgname in temporary_ignorepkgs) {
+				temporary_ignorepkgs_ += pkgname;
+			}
+			try {
+				// this will respond with trans_prepare_finished signal
+				daemon.start_sysupgrade_prepare (enable_downgrade, temporary_ignorepkgs_);
+			} catch (IOError e) {
+				stderr.printf ("IOError: %s\n", e.message);
+				success = false;
+				finish_transaction ();
 			}
 		}
 
@@ -747,11 +712,17 @@ namespace Pamac {
 							to_build.add (infos.name);
 						}
 					}
-				}
-				if (updates.repos_updates.length != 0) {
-					sysupgrade_simple (enable_downgrade);
+					if (updates.repos_updates.length != 0) {
+						sysupgrade_simple (enable_downgrade);
+					} else {
+						on_trans_prepare_finished (true);
+					}
 				} else {
-					on_trans_prepare_finished (true);
+					if (updates.repos_updates.length != 0) {
+						sysupgrade_simple (enable_downgrade);
+					} else {
+						finish_transaction ();
+					}
 				}
 			}
 		}
@@ -778,59 +749,24 @@ namespace Pamac {
 				// there only AUR packages to build so no need to prepare transaction
 				on_trans_prepare_finished (true);
 			} else {
-				success = false;
+				string [] to_install_ = {};
+				string [] to_remove_ = {};
+				string [] to_load_ = {};
+				foreach (unowned string name in to_install) {
+					to_install_ += name;
+				}
+				foreach (unowned string name in to_remove) {
+					to_remove_ += name;
+				}
+				foreach (unowned string path in to_load) {
+					to_load_ += path;
+				}
 				try {
-					success = daemon.trans_init (flags);
+					daemon.start_trans_prepare (flags, to_install_, to_remove_, to_load_);
 				} catch (IOError e) {
 					stderr.printf ("IOError: %s\n", e.message);
-				}
-				if (success) {
 					success = false;
-					foreach (unowned string name in to_install) {
-						try {
-							success = daemon.trans_add_pkg (name);
-						} catch (IOError e) {
-							stderr.printf ("IOError: %s\n", e.message);
-						}
-						if (!success) {
-							break;
-						}
-					}
-					foreach (unowned string name in to_remove) {
-						try {
-							success = daemon.trans_remove_pkg (name);
-						} catch (IOError e) {
-							stderr.printf ("IOError: %s\n", e.message);
-						}
-						if (!success) {
-							break;
-						}
-					}
-					foreach (unowned string path in to_load) {
-						try {
-							success = daemon.trans_load_pkg (path);
-						} catch (IOError e) {
-							stderr.printf ("IOError: %s\n", e.message);
-						}
-						if (!success) {
-							break;
-						}
-					}
-					if (success) {
-						try {
-							daemon.start_trans_prepare ();
-						} catch (IOError e) {
-							stderr.printf ("IOError: %s\n", e.message);
-							release ();
-							success = false;
-							finish_transaction ();
-						}
-					} else {
-						release ();
-						handle_error (get_current_error ());
-					}
-				} else {
-					handle_error (get_current_error ());
+					finish_transaction ();
 				}
 			}
 		}
@@ -995,7 +931,7 @@ namespace Pamac {
 			string action = dgettext (null, "Building packages") + "...";
 			reset_progress_box (action);
 			term.grab_focus ();
-			pulse_timeout_id = Timeout.add (500, (GLib.SourceFunc) progress_box.progressbar.pulse);
+			start_progressbar_pulse ();
 			important_details_outpout (true);
 			start_transaction ();
 			string[] cmds = {"yaourt", "-S"};
@@ -1028,7 +964,7 @@ namespace Pamac {
 			}
 			progress_box.hide ();
 			spawn_in_term ({"/usr/bin/echo", dgettext (null, "Transaction cancelled") + ".\n"});
-			dialog_textbuffer = new StringBuilder ();
+			warning_textbuffer = new StringBuilder ();
 		}
 
 		public void release () {
@@ -1037,9 +973,7 @@ namespace Pamac {
 			} catch (IOError e) {
 				stderr.printf ("IOError: %s\n", e.message);
 			}
-			foreach (unowned string pkgname in temporary_ignorepkgs) {
-				remove_ignorepkg (pkgname);
-			}
+			warning_textbuffer = new StringBuilder ();
 		}
 
 		public void stop_daemon () {
@@ -1146,7 +1080,7 @@ namespace Pamac {
 					break;
 				case 33: //Alpm.Event.Type.OPTDEP_REMOVAL
 					detailed_action = dgettext (null, "%s optionally requires %s").printf (details[0], details[1]);
-					dialog_textbuffer.append (detailed_action + "\n");
+					warning_textbuffer.append (detailed_action + "\n");
 					break;
 				case 34: //Alpm.Event.Type.DATABASE_MISSING
 					detailed_action = dgettext (null, "Database file for %s does not exist").printf (details[0]);
@@ -1369,7 +1303,7 @@ namespace Pamac {
 					} else {
 						line = dgettext (null, "Warning") + ": " + msg;
 					}
-					dialog_textbuffer.append (msg);
+					warning_textbuffer.append (msg);
 				}
 			}
 			if (line != null) {
@@ -1378,7 +1312,7 @@ namespace Pamac {
 		}
 
 		void show_warnings () {
-			if (dialog_textbuffer.len > 0) {
+			if (warning_textbuffer.len > 0) {
 				var dialog = new Gtk.Dialog.with_buttons (dgettext (null, "Warning"),
 														application_window,
 														Gtk.DialogFlags.MODAL | Gtk.DialogFlags.USE_HEADER_BAR);
@@ -1389,7 +1323,7 @@ namespace Pamac {
 				widget.can_default = true;
 				widget.has_default = true;
 				var scrolledwindow = new Gtk.ScrolledWindow (null, null);
-				var label = new Gtk.Label (dialog_textbuffer.str);
+				var label = new Gtk.Label (warning_textbuffer.str);
 				label.margin = 12;
 				scrolledwindow.visible = true;
 				label.visible = true;
@@ -1401,7 +1335,7 @@ namespace Pamac {
 				dialog.default_height = 300;
 				dialog.run ();
 				dialog.destroy ();
-				dialog_textbuffer = new StringBuilder ();
+				warning_textbuffer = new StringBuilder ();
 			}
 		}
 
@@ -1470,7 +1404,6 @@ namespace Pamac {
 						}
 						if (type == Type.BUILD) {
 							// there only AUR packages to build
-							release ();
 							on_trans_commit_finished (true);
 						} else {
 							// backup to_install and to_remove
@@ -1505,6 +1438,7 @@ namespace Pamac {
 					//handle_error (err);
 				}
 			} else {
+				warning_textbuffer = new StringBuilder ();
 				handle_error (get_current_error ());
 			}
 		}
@@ -1512,6 +1446,7 @@ namespace Pamac {
 		void on_trans_commit_finished (bool success) {
 			this.success = success;
 			if (success) {
+				show_warnings ();
 				if (to_build.length != 0) {
 					if (previous_to_install.length != 0
 							|| previous_to_remove.length != 0
@@ -1521,7 +1456,6 @@ namespace Pamac {
 					build_aur_packages ();
 				} else {
 					clear_previous_lists ();
-					show_warnings ();
 					if (sysupgrade_after_trans) {
 						sysupgrade_after_trans = false;
 						sysupgrade (false);
@@ -1546,6 +1480,7 @@ namespace Pamac {
 					}
 				}
 				clear_previous_lists ();
+				warning_textbuffer = new StringBuilder ();
 				handle_error (err);
 			}
 			total_download = 0;
@@ -1554,7 +1489,7 @@ namespace Pamac {
 		}
 
 		void on_term_child_exited (int status) {
-			Source.remove (pulse_timeout_id);
+			stop_progressbar_pulse ();
 			clear_previous_lists ();
 			to_build.remove_all ();
 			// let the time to the daemon to update databases
@@ -1601,7 +1536,7 @@ namespace Pamac {
 		}
 
 		void on_generate_mirrors_list_finished () {
-			Source.remove (pulse_timeout_id);
+			stop_progressbar_pulse ();
 			spawn_in_term ({"echo"});
 			// force a dbs refresh
 			start_refresh (true);