diff --git a/changelog.d/10343.bugfix b/changelog.d/10343.bugfix
new file mode 100644
index 000000000..53ccf79a8
--- /dev/null
+++ b/changelog.d/10343.bugfix
@@ -0,0 +1 @@
+Fix errors during backfill caused by previously purged redaction events. Contributed by Andreas Rammhold (@andir).
diff --git a/synapse/storage/databases/main/events.py b/synapse/storage/databases/main/events.py
index 897fa0663..08c580b0d 100644
--- a/synapse/storage/databases/main/events.py
+++ b/synapse/storage/databases/main/events.py
@@ -1580,11 +1580,11 @@ class PersistEventsStore:
         # invalidate the cache for the redacted event
         txn.call_after(self.store._invalidate_get_event_cache, event.redacts)
 
-        self.db_pool.simple_insert_txn(
+        self.db_pool.simple_upsert_txn(
             txn,
             table="redactions",
+            keyvalues={"event_id": event.event_id},
             values={
-                "event_id": event.event_id,
                 "redacts": event.redacts,
                 "received_ts": self._clock.time_msec(),
             },
diff --git a/synapse/storage/databases/main/purge_events.py b/synapse/storage/databases/main/purge_events.py
index ec6b1eb5d..eb4841830 100644
--- a/synapse/storage/databases/main/purge_events.py
+++ b/synapse/storage/databases/main/purge_events.py
@@ -215,6 +215,7 @@ class PurgeEventsStore(StateGroupWorkerStore, CacheInvalidationWorkerStore):
             "event_relations",
             "event_search",
             "rejections",
+            "redactions",
         ):
             logger.info("[purge] removing events from %s", table)