diff --git a/sapl/base/templatetags/common_tags.py b/sapl/base/templatetags/common_tags.py
index 8506669a4..9a60bf85e 100644
--- a/sapl/base/templatetags/common_tags.py
+++ b/sapl/base/templatetags/common_tags.py
@@ -84,6 +84,9 @@ def desc_operation(value):
 
 @register.filter
 def format_user(user):
+    if not user:
+        return ""
+
     if user.first_name:
         return user.first_name + " " + user.last_name + " (" + user.username + ")"
     else: