Index: /trunk/src/VBox/Main/src-client/ConsoleImpl2.cpp
===================================================================
--- /trunk/src/VBox/Main/src-client/ConsoleImpl2.cpp	(revision 85356)
+++ /trunk/src/VBox/Main/src-client/ConsoleImpl2.cpp	(revision 85357)
@@ -5861,4 +5861,21 @@
             case NetworkAttachmentType_Cloud:
             {
+                static const char *s_pszCloudExtPackName = "Oracle VM VirtualBox Extension Pack";
+                /*
+                 * Cloud network attachments do not work wihout installed extpack.
+                 * Without extpack support they won't work either.
+                 */
+# ifdef VBOX_WITH_EXTPACK
+                if (!mptrExtPackManager->i_isExtPackUsable(s_pszCloudExtPackName))
+# endif
+                {
+                    return VMSetError(VMR3GetVM(mpUVM), VERR_NOT_FOUND, RT_SRC_POS,
+                            N_("Implementation of the cloud network attachment not found!\n"
+                                "To fix this problem, either install the '%s' or switch to "
+                                "another network attachment type in the VM settings.\n"
+                                ),
+                            s_pszCloudExtPackName);
+                }
+
                 ComPtr<ICloudNetwork> network;
                 hrc = aNetworkAdapter->COMGETTER(CloudNetwork)(bstr.asOutParam());            H();