diff --git a/flask/app.py b/flask/app.py
index c30b439..4a8f90c 100644
--- a/flask/app.py
+++ b/flask/app.py
@@ -60,9 +60,10 @@ def generate_exception():
 @app.route('/user/<username>')
 def user_profile(username):
     print(f"User profile requested for {username}")
-    test = user_data[username]
+    test = user_data.get(username)
     if not test:
-        raise
+        logging.warning(f"User profile lookup failed for username '{username}'")
+        return jsonify({"error": f"User '{username}' not found"}), 404
     return jsonify({"message": f"Profile for {username}", "data": test})
 
 @app.route('/process', methods=['POST'])