Index: univention-directory-manager-modules/modules/univention/admin/uexceptions.py
===================================================================
--- univention-directory-manager-modules/modules/univention/admin/uexceptions.py	(Revision 45574)
+++ univention-directory-manager-modules/modules/univention/admin/uexceptions.py	(Arbeitskopie)
@@ -109,9 +109,9 @@
 class adGroupTypeChangeGlobalToUniversal(base):
 	message = _('The AD group type can not be changed from global to universal, because the group is member of another global group.')
 class adGroupTypeChangeDomainLocalToUniversal(base):
-	message = _("The AD group type can not be changed from domain local to universal, because the group is member of another domain local group.")
+	message = _("The AD group type can not be changed from domain local to universal, because the group has at least one domain local group as member.")
 class adGroupTypeChangeUniversalToGlobal(base):
-	message = _("The AD group type can not be changed from universal to global, because the group is member of another universal group.")
+	message = _("The AD group type can not be changed from universal to global, because the group has at least obe universal group as member.")
 
 class adGroupTypeChangeGlobalToDomainLocal(base):
 	message = _("The AD group type can not be changed from global to domain local.")
Index: univention-directory-manager-modules/modules/univention/admin/handlers/groups/group.py
===================================================================
--- univention-directory-manager-modules/modules/univention/admin/handlers/groups/group.py	(Revision 45574)
+++ univention-directory-manager-modules/modules/univention/admin/handlers/groups/group.py	(Arbeitskopie)
@@ -947,7 +947,7 @@
 		except ValueError:
 			return False
 
-	def _has_another_global_member(self):
+	def _is_member_of_global_group(self):
 		searchResult = self.lo.search(base=self.position.getDomain(), filter='(uniqueMember=%s)' % self.dn, attr=['univentionGroupType'])
 		for (dn,attr) in searchResult:
 			groupType = attr.get('univentionGroupType', [None])[0]
@@ -955,20 +955,30 @@
 				return True
 		return False
 
-	def _has_another_domain_local_member(self):
-		searchResult = self.lo.search(base=self.position.getDomain(), filter='(uniqueMember=%s)' % self.dn, attr=['univentionGroupType'])
-		for (dn,attr) in searchResult:
-			groupType = attr.get('univentionGroupType', [None])[0]
-			if self.__is_groupType_domain_local(groupType):
-				return True
+	def _has_domain_local_member(self):
+		for member_dn in self.oldattr.get('uniqueMember'):
+			searchResult = self.lo.search(base=member_dn, attr=['univentionGroupType'])
+			if searchResult:
+				(dn, attr) = searchResult
+				groupType = attr.get('univentionGroupType', [None])[0]
+				if self.__is_groupType_domain_local(groupType):
+					return True
+			else:
+				univention.debug.debug(univention.debug.ADMIN, univention.debug.ERROR, 'groups/group: uniqueMember %s not found during groupType check' % (member_dn,))
+				raise univention.admin.uexceptions.invalidChild
 		return False
 
-	def _has_another_universal_member(self):
-		searchResult = self.lo.search(base=self.position.getDomain(), filter='(uniqueMember=%s)' % self.dn, attr=['univentionGroupType'])
-		for (dn,attr) in searchResult:
-			groupType = attr.get('univentionGroupType', [None])[0]
-			if self.__is_groupType_universal(groupType):
-				return True
+	def _has_universal_member(self):
+		for member_dn in self.oldattr.get('uniqueMember'):
+			searchResult = self.lo.search(base=member_dn, attr=['univentionGroupType'])
+			if searchResult:
+				(dn, attr) = searchResult
+				groupType = attr.get('univentionGroupType', [None])[0]
+				if self.__is_groupType_universal(groupType):
+					return True
+			else:
+				univention.debug.debug(univention.debug.ADMIN, univention.debug.ERROR, 'groups/group: uniqueMember %s not found during groupType check' % (member_dn,))
+				raise univention.admin.uexceptions.invalidChild
 		return False
 
 	def check_ad_group_type_change(self):
@@ -1001,19 +1011,19 @@
 			# Global to universal:
 			#  This conversion is allowed only if the group that you want to change is not a member of
 			#  another global scope group.
-			if self._has_another_global_member():
+			if self._is_member_of_global_group():
 				raise univention.admin.uexceptions.adGroupTypeChangeGlobalToUniversal
 		elif self.__is_groupType_domain_local(old_groupType) and self.__is_groupType_universal(new_groupType):
 			# Domain local to universal:
 			#  This conversion is allowed only if the group that you want to change does not have
 			#  another domain local group as a member.
-			if self._has_another_domain_local_member():
+			if self._has_domain_local_member():
 				raise univention.admin.uexceptions.adGroupTypeChangeDomainLocalToUniversal
 		elif self.__is_groupType_universal(old_groupType) and self.__is_groupType_global(new_groupType):
 			# Universal to global:
 			#  This conversion is allowed only if the group that you want to change does not have
 			#  another universal group as a member.
-			if self._has_another_universal_member():
+			if self._has_universal_member():
 					raise univention.admin.uexceptions.adGroupTypeChangeUniversalToGlobal
 
 	def __generate_group_sid(self, gidNum):