diff --git a/server/vbv_lernwelt/competence/graphql/queries.py b/server/vbv_lernwelt/competence/graphql/queries.py
index 942842a8..1e949d45 100644
--- a/server/vbv_lernwelt/competence/graphql/queries.py
+++ b/server/vbv_lernwelt/competence/graphql/queries.py
@@ -55,7 +55,9 @@ class CompetenceCertificateQuery(object):
         root, info, id=None, slug=None, course_id=None, course_slug=None, user_id=None
     ):
         try:
-            course_session_user = CourseSessionUser.objects.get(user__id=user_id)
+            course_session_user = CourseSessionUser.objects.filter(
+                user__id=user_id
+            ).first()
         except CourseSessionUser.DoesNotExist:
             return None
 
diff --git a/server/vbv_lernwelt/shop/invoice/abacus.py b/server/vbv_lernwelt/shop/invoice/abacus.py
index 1bc7cd2d..201345d3 100644
--- a/server/vbv_lernwelt/shop/invoice/abacus.py
+++ b/server/vbv_lernwelt/shop/invoice/abacus.py
@@ -75,9 +75,11 @@ def create_customer_xml(checkout_information: CheckoutInformation):
         abacus_debitor_number=customer.abacus_debitor_number,
         last_name=checkout_information.last_name,
         first_name=checkout_information.first_name,
-        company_name=checkout_information.organisation_detail_name
-        if checkout_information.invoice_address == "org"
-        else "",
+        company_name=(
+            checkout_information.organisation_detail_name
+            if checkout_information.invoice_address == "org"
+            else ""
+        ),
         street=(
             checkout_information.organisation_street
             if checkout_information.invoice_address == "org"