diff --git a/ephios/core/models/events.py b/ephios/core/models/events.py
index 844937ef7..9d4595265 100644
--- a/ephios/core/models/events.py
+++ b/ephios/core/models/events.py
@@ -263,7 +263,9 @@ class Shift(DatetimeDisplayMixin, Model):
 
     structure_slug = SlugField(_("structure"))
     structure_configuration = JSONField(
-        default=dict, encoder=CustomJSONEncoder, decoder=CustomJSONDecoder
+        default=dict,
+        encoder=CustomJSONEncoder,
+        decoder=CustomJSONDecoder,
     )
 
     class Meta:
@@ -272,7 +274,7 @@ class Meta:
         ordering = ("meeting_time", "start_time", "id")
         db_table = "shift"
 
-    @property
+    @cached_property
     def signup_flow(self) -> "AbstractSignupFlow":
         from ephios.core.signup.flow import signup_flow_from_slug
 
@@ -304,6 +306,28 @@ def structure(self) -> "AbstractShiftStructure":
 
             return FallbackShiftStructure(self, event=event)
 
+    def _clear_cached_signup_objects(self):
+        """
+        when changing data on the shift, cached info in the signup flow or structure might become outdated,
+        so we clear the cached versions. (most relevant to tests, as we use new instances every request)
+        """
+        try:
+            del self.structure
+        except AttributeError:
+            pass
+        try:
+            del self.signup_flow
+        except AttributeError:
+            pass
+
+    def save(self, *args, **kwargs):
+        self._clear_cached_signup_objects()
+        return super().save(*args, **kwargs)
+
+    def refresh_from_db(self, using=None, fields=None):
+        self._clear_cached_signup_objects()
+        return super().refresh_from_db(using, fields)
+
     def get_participants(self, with_state_in=frozenset({AbstractParticipation.States.CONFIRMED})):
         for participation in self.participations.filter(state__in=with_state_in):
             yield participation.participant
diff --git a/ephios/core/services/matching.py b/ephios/core/services/matching.py
index aa70b8c16..51f55c091 100644
--- a/ephios/core/services/matching.py
+++ b/ephios/core/services/matching.py
@@ -18,7 +18,7 @@ class Position:
     designated_for: Collection[AbstractParticipant]  # designated by disposition
     preferred_by: Collection[AbstractParticipant]  # preferred by participant (less important)
     label: Optional[str] = None
-    aux_score: float = 0.0  # additional score control
+    aux_score: float = 0.0  # additional score control in range [0,1]
 
     def __post_init__(self):
         self.required_qualifications = frozenset(self.required_qualifications)
diff --git a/ephios/core/signup/flow/participant_validation.py b/ephios/core/signup/flow/participant_validation.py
index bd18fdc08..930d2b2d4 100644
--- a/ephios/core/signup/flow/participant_validation.py
+++ b/ephios/core/signup/flow/participant_validation.py
@@ -11,6 +11,9 @@
 class BaseSignupError(Exception):
     """Superclass of errors used in the signup mechanism."""
 
+    def __init__(self, message):
+        self.message = message
+
 
 class SignupDisallowedError(BaseSignupError):
     """
diff --git a/ephios/plugins/complexsignup/structure.py b/ephios/plugins/complexsignup/structure.py
index eb5e06aaa..70a61c288 100644
--- a/ephios/plugins/complexsignup/structure.py
+++ b/ephios/plugins/complexsignup/structure.py
@@ -359,6 +359,7 @@ def _search_block(
                 preferred_by=preferred_by,
                 required=required,
                 label=label,
+                aux_score=1,
             )
             participation = matching.participation_for_position(match_id) if matching else None
             signup_stats += SignupStats.ZERO.replace(
diff --git a/ephios/settings.py b/ephios/settings.py
index 2ff9c5381..da6e4436c 100644
--- a/ephios/settings.py
+++ b/ephios/settings.py
@@ -466,3 +466,8 @@ def GET_SITE_URL():
 
 if env.bool("TRUST_X_FORWARDED_PROTO", default=False):
     SECURE_PROXY_SSL_HEADER = ("HTTP_X_FORWARDED_PROTO", "https")
+
+# Transitional/deprecated settings
+FORMS_URLFIELD_ASSUME_HTTPS = (
+    True  # https://docs.djangoproject.com/en/5.1/ref/settings/#forms-urlfield-assume-https
+)
diff --git a/tests/core/services/test_matching.py b/tests/core/services/test_matching.py
index 24cbfdadc..74f736347 100644
--- a/tests/core/services/test_matching.py
+++ b/tests/core/services/test_matching.py
@@ -7,8 +7,8 @@ def test_match_participants_to_positions(qualifications):
     # create 3 participants
     ann = PlaceholderParticipant("Ann", {qualifications.nfs}, None, None)
     ben = PlaceholderParticipant("Ben", {qualifications.rs, qualifications.ce}, None, None)
-    leader = Position("Führer", True, {qualifications.nfs}, [])
-    driver = Position("Fahrer", True, {qualifications.rs, qualifications.c}, [])
+    leader = Position("Führer", True, {qualifications.nfs}, [], [])
+    driver = Position("Fahrer", True, {qualifications.rs, qualifications.c}, [], [])
 
     assert match_participants_to_positions([], []).pairings == set()
     assert match_participants_to_positions([ben], []).pairings == set()
@@ -51,10 +51,10 @@ def test_maximise_number_of_matches_in_adverse_case():
     z = PlaceholderParticipant("Z", {q_d}, None, None)
 
     positions = [
-        Position("A", False, {q_a}, []),
-        Position("B", False, {q_b}, [w]),
-        Position("C", False, {q_c}, [x]),
-        Position("D", False, {q_d}, [y]),
+        Position("A", False, {q_a}, [], []),
+        Position("B", False, {q_b}, [], [w]),
+        Position("C", False, {q_c}, [], [x]),
+        Position("D", False, {q_d}, [], [y]),
     ]
     participants = [w, x, y, z]