2 files changed, 8 insertions, 6 deletions
diff --git a/synapse/push/bulk_push_rule_evaluator.py b/synapse/push/bulk_push_rule_evaluator.py
index 0622a37ae8..009d8e77b0 100644
--- a/synapse/push/bulk_push_rule_evaluator.py
+++ b/synapse/push/bulk_push_rule_evaluator.py
@@ -232,6 +232,8 @@ class BulkPushRuleEvaluator:
                 # that user, as they might not be already joined.
                 if event.type == EventTypes.Member and event.state_key == uid:
                     display_name = event.content.get("displayname", None)
+                    if not isinstance(display_name, str):
+                        display_name = None
 
             if count_as_unread:
                 # Add an element for the current user if the event needs to be marked as
@@ -268,7 +270,7 @@ def _condition_checker(
     evaluator: PushRuleEvaluatorForEvent,
     conditions: List[dict],
     uid: str,
-    display_name: str,
+    display_name: Optional[str],
     cache: Dict[str, bool],
 ) -> bool:
     for cond in conditions:
diff --git a/synapse/push/push_rule_evaluator.py b/synapse/push/push_rule_evaluator.py
index 7a8dc63976..7f68092ec5 100644
--- a/synapse/push/push_rule_evaluator.py
+++ b/synapse/push/push_rule_evaluator.py
@@ -18,7 +18,7 @@ import re
 from typing import Any, Dict, List, Optional, Pattern, Tuple, Union
 
 from synapse.events import EventBase
-from synapse.types import UserID
+from synapse.types import JsonDict, UserID
 from synapse.util import glob_to_regex, re_word_boundary
 from synapse.util.caches.lrucache import LruCache
 
@@ -129,7 +129,7 @@ class PushRuleEvaluatorForEvent:
         self._value_cache = _flatten_dict(event)
 
     def matches(
-        self, condition: Dict[str, Any], user_id: str, display_name: str
+        self, condition: Dict[str, Any], user_id: str, display_name: Optional[str]
     ) -> bool:
         if condition["kind"] == "event_match":
             return self._event_match(condition, user_id)
@@ -172,7 +172,7 @@ class PushRuleEvaluatorForEvent:
 
             return _glob_matches(pattern, haystack)
 
-    def _contains_display_name(self, display_name: str) -> bool:
+    def _contains_display_name(self, display_name: Optional[str]) -> bool:
         if not display_name:
             return False
 
@@ -222,7 +222,7 @@ def _glob_matches(glob: str, value: str, word_boundary: bool = False) -> bool:
 
 
 def _flatten_dict(
-    d: Union[EventBase, dict],
+    d: Union[EventBase, JsonDict],
     prefix: Optional[List[str]] = None,
     result: Optional[Dict[str, str]] = None,
 ) -> Dict[str, str]:
@@ -233,7 +233,7 @@ def _flatten_dict(
     for key, value in d.items():
         if isinstance(value, str):
             result[".".join(prefix + [key])] = value.lower()
-        elif hasattr(value, "items"):
+        elif isinstance(value, dict):
             _flatten_dict(value, prefix=(prefix + [key]), result=result)
 
     return result