diff --git modules/univention/office365/azure_auth.py modules/univention/office365/azure_auth.py
index 05c8c39..d49a250 100644
--- modules/univention/office365/azure_auth.py
+++ modules/univention/office365/azure_auth.py
@@ -357,6 +357,7 @@ class AzureAuth(object):
 		ids = self.load_azure_ids(adconnection_alias)
 		try:
 			self.client_id = ids["client_id"]
+			self.client_secret = ids["client_secret"]
 			self.adconnection_id = ids["adconnection_id"]
 			self.reply_url = ids["reply_url"]
 			self.domain = ids["domain"]
@@ -611,16 +612,11 @@ class AzureAuth(object):
 		return adconnection_id
 
 	def retrieve_access_token(self):
-		assertion = self._get_client_assertion()
-
 		post_form = {
 			'resource': resource_url,
 			'client_id': self.client_id,
-			'client_assertion_type': 'urn:ietf:params:oauth:client-assertion-type:jwt-bearer',
-			'client_assertion': assertion,
 			'grant_type': 'client_credentials',
-			'redirect_uri': self.reply_url,
-			'scope': SCOPE
+			'client_secret': self.client_secret
 		}
 		url = oauth2_token_url.format(adconnection_id=self.adconnection_id)