--- a/ucs-school-old-homedirs/remove-old-homedirs.py	
+++ a/ucs-school-old-homedirs/remove-old-homedirs.py	
@@ -40,7 +40,7 @@ import univention.debug
 
 name = 'remove-old-homedirs'
 description = 'moves directories of removed users away from home'
-filter = '(objectClass=ucsschoolType)'
+filter = '(&(objectClass=ucsschoolType)(uid=*))'
 attributes = ["posixAccount"]
 modrdn = '1'