diff --git a/modules/node/handler/cms_node_type_webform_manager.e b/modules/node/handler/cms_node_type_webform_manager.e
index 1b0fc94..69c9496 100644
--- a/modules/node/handler/cms_node_type_webform_manager.e
+++ b/modules/node/handler/cms_node_type_webform_manager.e
@@ -21,7 +21,6 @@ feature -- Forms ...
 			tselect: WSF_FORM_SELECT
 			opt: WSF_FORM_SELECT_OPTION
 			cms_format: CMS_EDITOR_CONTENT_FORMAT
-			l_uri: detachable READABLE_STRING_8
 		do
 			create cms_format
 
@@ -94,6 +93,15 @@ feature -- Forms ...
 
 			f.extend (fset)
 
+				-- Path alias		
+			populate_form_with_path_alias (response, f, a_node)
+		end
+
+	populate_form_with_path_alias (response: NODE_RESPONSE; f: CMS_FORM; a_node: detachable CMS_NODE)
+		local
+			ti: WSF_FORM_TEXT_INPUT
+			l_uri: detachable READABLE_STRING_8
+		do
 				-- Path alias		
 			create ti.make ("path_alias")
 			ti.set_label ("Path")
@@ -106,32 +114,32 @@ feature -- Forms ...
 				end
 				ti.set_text_value (l_uri)
 				ti.set_description ("Optionally specify an alternative URL path by which this content can be accessed. For example, type 'about' when writing an about page. Use a relative path or the URL alias won't work.")
-				ti.set_validation_action (agent (fd: WSF_FORM_DATA; ia_response: NODE_RESPONSE; ia_node: CMS_NODE)
-						do
-							if
-								attached fd.string_item ("path_alias") as f_path_alias
-							then
-								if ia_response.api.is_valid_path_alias (f_path_alias) then
-										-- Ok.
-								elseif f_path_alias.is_empty then
-										-- Ok
-								elseif f_path_alias.starts_with_general ("/") then
-									fd.report_invalid_field ("path_alias", "Path alias should not start with a slash '/' .")
-								elseif f_path_alias.has_substring ("://") then
-									fd.report_invalid_field ("path_alias", "Path alias should not be absolute url .")
-								else
-										-- TODO: implement full path alias validation
-								end
-								if
-									attached ia_response.api.source_of_path_alias (f_path_alias) as l_aliased_location and then
-									not l_aliased_location.same_string (ia_response.node_api.node_path (ia_node))
-								then
-									fd.report_invalid_field ("path_alias", "Path is already aliased to location %"" + ia_response.link (Void, l_aliased_location, Void) + "%" !")
-								end
-							end
-						end(?, response, a_node)
-					)
 			end
+			ti.set_validation_action (agent (fd: WSF_FORM_DATA; ia_response: NODE_RESPONSE; ia_node: detachable CMS_NODE)
+					do
+						if
+							attached fd.string_item ("path_alias") as f_path_alias
+						then
+							if ia_response.api.is_valid_path_alias (f_path_alias) then
+									-- Ok.
+							elseif f_path_alias.is_empty then
+									-- Ok
+							elseif f_path_alias.starts_with_general ("/") then
+								fd.report_invalid_field ("path_alias", "Path alias should not start with a slash '/' .")
+							elseif f_path_alias.has_substring ("://") then
+								fd.report_invalid_field ("path_alias", "Path alias should not be absolute url .")
+							else
+									-- TODO: implement full path alias validation
+							end
+							if
+								attached ia_response.api.source_of_path_alias (f_path_alias) as l_aliased_location and then
+								((ia_node /= Void and then ia_node.has_id) implies not l_aliased_location.same_string (ia_response.node_api.node_path (ia_node)))
+							then
+								fd.report_invalid_field ("path_alias", "Path is already aliased to location %"" + ia_response.link (Void, l_aliased_location, Void) + "%" !")
+							end
+						end
+					end(?, response, a_node)
+				)
 			if
 				attached f.fields_by_name ("title") as l_title_fields and then
 				attached l_title_fields.first as l_title_field
@@ -142,6 +150,7 @@ feature -- Forms ...
 			end
 		end
 
+
 	update_node	(response: NODE_RESPONSE; fd: WSF_FORM_DATA; a_node: CMS_NODE)
 		local
 			b,s: detachable READABLE_STRING_8
diff --git a/src/service/cms_module.e b/src/service/cms_module.e
index 1791353..fcb3574 100644
--- a/src/service/cms_module.e
+++ b/src/service/cms_module.e
@@ -79,14 +79,28 @@ feature {CMS_API} -- Module management
 	is_installed (api: CMS_API): BOOLEAN
 			-- Is Current module installed?
 		do
-			Result := attached api.storage.custom_value ("is_initialized", "module-" + name) as v and then v.is_case_insensitive_equal_general ("yes")
+			if attached api.storage.custom_value ("is_initialized", "module-" + name) as v then
+				if v.is_case_insensitive_equal_general (version) then
+					Result := True
+				elseif v.is_case_insensitive_equal_general ("yes") then
+						-- Backward compatibility.
+					Result := True
+				elseif v.is_case_insensitive_equal_general ("no") then
+						-- Probably a module that was installed, but now uninstalled.
+					Result := False
+				else
+						-- Maybe a different version is installed.
+						-- For now, let's assume this is installed.
+					Result := True
+				end
+			end
 		end
 
 	install (api: CMS_API)
 		require
 			is_not_installed: not is_installed (api)
 		do
-			api.storage.set_custom_value ("is_initialized", "yes", "module-" + name)
+			api.storage.set_custom_value ("is_initialized", version, "module-" + name)
 		end
 
 	uninstall (api: CMS_API)
@@ -151,6 +165,10 @@ feature -- Hooks
 			create Result.make_empty
 		end
 
+invariant
+	name_set: not name.is_whitespace
+	version_set: not version.is_whitespace
+
 note
 	copyright: "2011-2015, Jocelyn Fiat, Javier Velilla, Eiffel Software and others"
 	license: "Eiffel Forum License v2 (see http://www.eiffel.com/licensing/forum.txt)"