Index: umc/join.xml
===================================================================
--- umc/join.xml	(Revision 77738)
+++ umc/join.xml	(Arbeitskopie)
@@ -7,7 +7,7 @@
 		<categories>
 			<category name="domain"/>
 		</categories>
-		<command name="join/locked" function="dpkg_locked"/>
+		<command name="join/locked" function="updater_or_dpkg_lock"/>
 		<command name="join/scripts/query" function="query"/>
 		<command name="join/logview" function="logview"/>
 		<command name="join/joined" function="joined"/>
Index: umc/python/join/__init__.py
===================================================================
--- umc/python/join/__init__.py	(Revision 77738)
+++ umc/python/join/__init__.py	(Arbeitskopie)
@@ -50,6 +50,7 @@
 from univention.management.console.config import ucr
 from univention.management.console.modules.decorators import simple_response, sanitize
 from univention.management.console.modules.sanitizers import StringSanitizer, ListSanitizer, BooleanSanitizer
+from univention.updater.locking import UpdaterLock
 
 _ = umc.Translation('univention-management-console-module-join').translate
 
@@ -279,11 +280,15 @@
 		self.progress_state = Progress()
 
 	@simple_response
-	def dpkg_locked(self):
-		"""Do not execute join scripts when dpkg is running (e.g. via
-		App Center)
+	def updater_or_dpkg_lock(self):
+		"""Do not execute join scripts when updater or dpkg
+		are running (e.g. via App Center)
 		"""
-		return self._dpkg_locked()
+		try:
+			with UpdaterLock():
+				return self._dpkg_locked()
+		except SystemExit:
+			return True
 
 	def _dpkg_locked(self):
 		fd = apt_pkg.get_lock('/var/lib/dpkg/lock')