Index: libs/protocol_p.h
===================================================================
--- libs/protocol_p.h	(révision 1087510)
+++ libs/protocol_p.h	(révision 1087511)
@@ -31,6 +31,7 @@
 // D-Bus service names
 #define AKONADI_DBUS_SERVER_SERVICE "org.freedesktop.Akonadi"
 #define AKONADI_DBUS_CONTROL_SERVICE "org.freedesktop.Akonadi.Control"
+#define AKONADI_DBUS_CONTROL_SERVICE_LOCK "org.freedesktop.Akonadi.Control.lock"
 
 #define AKONADI_DBUS_AGENTMANAGER_PATH "/AgentManager"
 
Index: server/control/main.cpp
===================================================================
--- server/control/main.cpp	(révision 1087510)
+++ server/control/main.cpp	(révision 1087511)
@@ -52,20 +52,31 @@
   app.setDescription( "Akonadi Control Process\nDo not run this manually, use 'akonadictl' instead to start/stop Akonadi." );
   app.parseCommandLine();
 
-  if ( !QDBusConnection::sessionBus().registerService( AKONADI_DBUS_CONTROL_SERVICE ) ) {
+  // try to aquire the lock first, that means there is no second instance trying to start up at the same time
+  if ( !QDBusConnection::sessionBus().registerService( AKONADI_DBUS_CONTROL_SERVICE_LOCK ) ) {
     // We couldn't register. Most likely, it's already running.
     const QString lastError = QDBusConnection::sessionBus().lastError().message();
     if (lastError.isEmpty())
-      akFatal() << "Unable to register service as" << AKONADI_DBUS_CONTROL_SERVICE << "Maybe it's already running?";
+      akFatal() << "Unable to register service as" << AKONADI_DBUS_CONTROL_SERVICE_LOCK << "Maybe it's already running?";
     else
-      akFatal() << "Unable to register service as" << AKONADI_DBUS_CONTROL_SERVICE << "Error was:" << lastError;
+      akFatal() << "Unable to register service as" << AKONADI_DBUS_CONTROL_SERVICE_LOCK << "Error was:" << lastError;
   }
 
+  // older Akonadi server versions don't use the lock service yet, so check if one is already running before we try to start another one
+  if ( QDBusConnection::sessionBus().interface()->isServiceRegistered( AKONADI_DBUS_CONTROL_SERVICE ) )
+    akFatal() << "Another Akonadi control process is already running.";
+
   new ControlManager;
 
   sAgentManager = new AgentManager;
   AkonadiCrash::setEmergencyMethod( crashHandler );
 
+  // register the real service name once everything is up an running
+  if ( !QDBusConnection::sessionBus().registerService( AKONADI_DBUS_CONTROL_SERVICE ) ) {
+    // besides a race with an older Akonadi server I have no idea how we could possibly get here...
+    akFatal() << "Unable to register service as" << AKONADI_DBUS_CONTROL_SERVICE << "despite having the lock. Error was:" << QDBusConnection::sessionBus().lastError().message();
+  }
+
   int retval = app.exec();
 
   delete sAgentManager;
Index: server/src/main.cpp
===================================================================
--- server/src/main.cpp	(révision 1087510)
+++ server/src/main.cpp	(révision 1087511)
@@ -58,7 +58,7 @@
     app.parseCommandLine();
 
     if ( !app.commandLineArguments().count( "start-without-control" ) &&
-         !QDBusConnection::sessionBus().interface()->isServiceRegistered( QLatin1String(AKONADI_DBUS_CONTROL_SERVICE) ) ) {
+         !QDBusConnection::sessionBus().interface()->isServiceRegistered( QLatin1String(AKONADI_DBUS_CONTROL_SERVICE_LOCK) ) ) {
       akError() << "Akonadi control process not found - aborting.";
       akFatal() << "If you started akonadiserver manually, try 'akonadictl start' instead.";
     }