diff --git a/ucs-school-umc-exam/umc/python/schoolexam/__init__.py b/ucs-school-umc-exam/umc/python/schoolexam/__init__.py
index 39518be..8c872aa 100644
--- a/ucs-school-umc-exam/umc/python/schoolexam/__init__.py
+++ b/ucs-school-umc-exam/umc/python/schoolexam/__init__.py
@@ -283,6 +283,7 @@ class Instance(SchoolBaseModule):
 				MODULE.info('waiting for replication to be finished, %s user objects missing' % (len(examUsers) - len(usersReplicated)))
 				for idn in examUsers - usersReplicated:
 					try:
+						ldap_user_read.search(base=idn, scope='base', required=True)
 						# try to open the user
 						iuser = util.distribution.openRecipients(idn, ldap_user_read)
 						if iuser: