diff --git a/connaisseur/flask_application.py b/connaisseur/flask_application.py
index b901519fd..d6528d0e8 100644
--- a/connaisseur/flask_application.py
+++ b/connaisseur/flask_application.py
@@ -55,8 +55,8 @@ def handle_alert_config_error(err):
     "mutate_requests_total",
     "Total number of mutate requests",
     labels={
-        "allowed": lambda r: r.get_json(silent=True)["response"]["allowed"],
-        "status_code": lambda r: r.get_json(silent=True)["response"]["status"]["code"],
+        "allowed": lambda r: metrics_label(r, "allowed"),
+        "status_code": lambda r: metrics_label(r, "status_code"),
     },
 )
 def mutate():
@@ -92,6 +92,16 @@ def mutate():
     return jsonify(response)
 
 
+def metrics_label(response, label):
+    l = response.get_json(silent=True)
+    if l:
+        if label == "allowed":
+            return l["response"]["allowed"]
+        elif label == "status_code":
+            return l["response"]["status"]["code"]
+    return l
+
+
 # health probe
 @APP.route("/health", methods=["GET", "POST"])
 @metrics.do_not_track()
diff --git a/tests/test_flask_application.py b/tests/test_flask_application.py
index 21eba40c7..833be2338 100644
--- a/tests/test_flask_application.py
+++ b/tests/test_flask_application.py
@@ -116,11 +116,13 @@ def test_mutate_calls_send_alert_for_invalid_admission_request(
 
 
 def test_healthz():
-    assert pytest.fa.healthz() == ("", 200)
+    with pytest.fa.APP.test_request_context():
+        assert pytest.fa.healthz() == ("", 200)
 
 
 def test_readyz():
-    assert pytest.fa.readyz() == ("", 200)
+    with pytest.fa.APP.test_request_context():
+        assert pytest.fa.readyz() == ("", 200)
 
 
 @pytest.mark.parametrize(
@@ -231,8 +233,9 @@ def test_error_handler(
 
     mocker.patch("connaisseur.flask_application.__admit", return_value=True)
     mock_function = mocker.patch(**function)
-    client = pytest.fa.APP.test_client()
-    mock_request_data = fix.get_admreq("deployments")
-    response = client.post("/mutate", json=mock_request_data)
-    assert response.status_code == 500
-    assert response.get_data().decode() == err
+    with pytest.fa.APP.test_request_context():
+        client = pytest.fa.APP.test_client()
+        mock_request_data = fix.get_admreq("deployments")
+        response = client.post("/mutate", json=mock_request_data)
+        assert response.status_code == 500
+        assert response.get_data().decode() == err