diff --git a/changelog.d/16725.bugfix b/changelog.d/16725.bugfix
new file mode 100644
index 0000000000..42dc249fb9
--- /dev/null
+++ b/changelog.d/16725.bugfix
@@ -0,0 +1 @@
+Fix a bug introduced in Synapse 1.7.2 where rooms whose power levels lacked an `events` field could not be upgraded.
diff --git a/synapse/handlers/room.py b/synapse/handlers/room.py
index f865bed1ec..2823ca6f0d 100644
--- a/synapse/handlers/room.py
+++ b/synapse/handlers/room.py
@@ -549,7 +549,7 @@ class RoomCreationHandler:
except (TypeError, ValueError):
ban = 50
needed_power_level = max(
- state_default_int, ban, max(event_power_levels.values())
+ state_default_int, ban, max(event_power_levels.values(), default=0)
)
# Get the user's current power level, this matches the logic in get_user_power_level,
diff --git a/tests/rest/client/test_upgrade_room.py b/tests/rest/client/test_upgrade_room.py
index 0b4c691318..28f772261b 100644
--- a/tests/rest/client/test_upgrade_room.py
+++ b/tests/rest/client/test_upgrade_room.py
@@ -246,6 +246,34 @@ class UpgradeRoomTest(unittest.HomeserverTestCase):
# We should now have an integer power level.
self.assertEqual(new_power_levels["users"][self.creator], 100, new_power_levels)
+ def test_events_field_missing(self) -> None:
+ """Regression test for https://github.com/matrix-org/synapse/issues/16715."""
+ # Create a new room.
+ room_id = self.helper.create_room_as(
+ self.creator, tok=self.creator_token, room_version="10"
+ )
+ self.helper.join(room_id, self.other, tok=self.other_token)
+
+ # Retrieve the room's current power levels.
+ power_levels = self.helper.get_state(
+ room_id,
+ "m.room.power_levels",
+ tok=self.creator_token,
+ )
+
+ # Remove the events field and re-set the power levels.
+ del power_levels["events"]
+ self.helper.send_state(
+ room_id,
+ "m.room.power_levels",
+ body=power_levels,
+ tok=self.creator_token,
+ )
+
+ # Upgrade the room. Check the homeserver reports success.
+ channel = self._upgrade_room(room_id=room_id)
+ self.assertEqual(200, channel.code, channel.result)
+
def test_space(self) -> None:
"""Test upgrading a space."""
|
