diff --git a/changelog.d/15298.bugfix b/changelog.d/15298.bugfix
new file mode 100644
index 0000000000..8f29b08444
--- /dev/null
+++ b/changelog.d/15298.bugfix
@@ -0,0 +1 @@
+Fix a bug in which the [`POST /_matrix/client/v3/rooms/{roomId}/report/{eventId}`](https://spec.matrix.org/v1.6/client-server-api/#post_matrixclientv3roomsroomidreporteventid) endpoint would return the wrong error if the user did not have permission to view the event. This aligns Synapse's implementation with [MSC2249](https://github.com/matrix-org/matrix-spec-proposals/pull/2249).
\ No newline at end of file
diff --git a/changelog.d/15300.bugfix b/changelog.d/15300.bugfix
new file mode 100644
index 0000000000..8f29b08444
--- /dev/null
+++ b/changelog.d/15300.bugfix
@@ -0,0 +1 @@
+Fix a bug in which the [`POST /_matrix/client/v3/rooms/{roomId}/report/{eventId}`](https://spec.matrix.org/v1.6/client-server-api/#post_matrixclientv3roomsroomidreporteventid) endpoint would return the wrong error if the user did not have permission to view the event. This aligns Synapse's implementation with [MSC2249](https://github.com/matrix-org/matrix-spec-proposals/pull/2249).
\ No newline at end of file
diff --git a/changelog.d/15301.bugfix b/changelog.d/15301.bugfix
new file mode 100644
index 0000000000..c8f3628d34
--- /dev/null
+++ b/changelog.d/15301.bugfix
@@ -0,0 +1,3 @@
+Fix a bug introduced in Synapse 1.75.0rc1 where the [SQLite port_db script](https://matrix-org.github.io/synapse/latest/postgres.html#porting-from-sqlite)
+would fail to open the SQLite database.
+
diff --git a/docs/upgrade.md b/docs/upgrade.md
index f06e874054..f14444a400 100644
--- a/docs/upgrade.md
+++ b/docs/upgrade.md
@@ -88,6 +88,18 @@ process, for example:
     dpkg -i matrix-synapse-py3_1.3.0+stretch1_amd64.deb
     ```
 
+# Upgrading to v1.80.0
+
+## Reporting events error code change
+
+Before this update, the
+[`POST /_matrix/client/v3/rooms/{roomId}/report/{eventId}`](https://spec.matrix.org/v1.6/client-server-api/#post_matrixclientv3roomsroomidreporteventid)
+endpoint would return a `403` if a user attempted to report an event that they did not have access to.
+This endpoint will now return a `404` in this case instead.
+
+Clients that implement event reporting should check that their error handling code will handle this
+change.
+
 # Upgrading to v1.79.0
 
 ## The `on_threepid_bind` module callback method has been deprecated
diff --git a/synapse/_scripts/synapse_port_db.py b/synapse/_scripts/synapse_port_db.py
index 2c9cbf8b27..78d76d38ad 100755
--- a/synapse/_scripts/synapse_port_db.py
+++ b/synapse/_scripts/synapse_port_db.py
@@ -1329,7 +1329,7 @@ def main() -> None:
     sqlite_config = {
         "name": "sqlite3",
         "args": {
-            "database": "file:{}?mode=rw".format(args.sqlite_database),
+            "database": args.sqlite_database,
             "cp_min": 1,
             "cp_max": 1,
             "check_same_thread": False,
diff --git a/synapse/handlers/events.py b/synapse/handlers/events.py
index 68c07f0265..33359f6ed7 100644
--- a/synapse/handlers/events.py
+++ b/synapse/handlers/events.py
@@ -159,15 +159,16 @@ class EventHandler:
         Returns:
             An event, or None if there is no event matching this ID.
         Raises:
-            SynapseError if there was a problem retrieving this event, or
-            AuthError if the user does not have the rights to inspect this
-            event.
+            AuthError: if the user does not have the rights to inspect this event.
         """
         redact_behaviour = (
             EventRedactBehaviour.as_is if show_redacted else EventRedactBehaviour.redact
         )
         event = await self.store.get_event(
-            event_id, check_room_id=room_id, redact_behaviour=redact_behaviour
+            event_id,
+            check_room_id=room_id,
+            redact_behaviour=redact_behaviour,
+            allow_none=True,
         )
 
         if not event:
diff --git a/synapse/rest/client/report_event.py b/synapse/rest/client/report_event.py
index 9be5860221..ac1a63ca27 100644
--- a/synapse/rest/client/report_event.py
+++ b/synapse/rest/client/report_event.py
@@ -16,7 +16,7 @@ import logging
 from http import HTTPStatus
 from typing import TYPE_CHECKING, Tuple
 
-from synapse.api.errors import Codes, NotFoundError, SynapseError
+from synapse.api.errors import AuthError, Codes, NotFoundError, SynapseError
 from synapse.http.server import HttpServer
 from synapse.http.servlet import RestServlet, parse_json_object_from_request
 from synapse.http.site import SynapseRequest
@@ -62,12 +62,18 @@ class ReportEventRestServlet(RestServlet):
                 Codes.BAD_JSON,
             )
 
-        event = await self._event_handler.get_event(
-            requester.user, room_id, event_id, show_redacted=False
-        )
+        try:
+            event = await self._event_handler.get_event(
+                requester.user, room_id, event_id, show_redacted=False
+            )
+        except AuthError:
+            # The event exists, but this user is not allowed to access this event.
+            event = None
+
         if event is None:
             raise NotFoundError(
-                "Unable to report event: it does not exist or you aren't able to see it."
+                "Unable to report event: "
+                "it does not exist or you aren't able to see it."
             )
 
         await self.store.add_event_report(
diff --git a/synapse/storage/databases/main/events_worker.py b/synapse/storage/databases/main/events_worker.py
index 20b7a68362..0cf46626d2 100644
--- a/synapse/storage/databases/main/events_worker.py
+++ b/synapse/storage/databases/main/events_worker.py
@@ -805,7 +805,6 @@ class EventsWorkerStore(SQLBaseStore):
                 # the events have been redacted, and if so pulling the redaction event
                 # out of the database to check it.
                 #
-                missing_events = {}
                 try:
                     # Try to fetch from any external cache. We already checked the
                     # in-memory cache above.
diff --git a/tests/rest/client/test_report_event.py b/tests/rest/client/test_report_event.py
index 1250685d39..b88f1d61a0 100644
--- a/tests/rest/client/test_report_event.py
+++ b/tests/rest/client/test_report_event.py
@@ -84,6 +84,48 @@ class ReportEventTestCase(unittest.HomeserverTestCase):
             access_token=self.other_user_tok,
         )
         self.assertEqual(404, channel.code, msg=channel.result["body"])
+        self.assertEqual(
+            "Unable to report event: it does not exist or you aren't able to see it.",
+            channel.json_body["error"],
+            msg=channel.result["body"],
+        )
+
+    def test_cannot_report_event_if_not_in_room(self) -> None:
+        """
+        Tests that we don't accept event reports for events that exist, but for which
+        the reporter should not be able to view (because they are not in the room).
+        """
+        # Have the admin user create a room (the "other" user will not join this room).
+        new_room_id = self.helper.create_room_as(tok=self.admin_user_tok)
+
+        # Have the admin user send an event in this room.
+        response = self.helper.send_event(
+            new_room_id,
+            "m.room.message",
+            content={
+                "msgtype": "m.text",
+                "body": "This event has some bad words in it! Flip!",
+            },
+            tok=self.admin_user_tok,
+        )
+        event_id = response["event_id"]
+
+        # Have the "other" user attempt to report it. Perhaps they found the event ID
+        # in a screenshot or something...
+        channel = self.make_request(
+            "POST",
+            f"rooms/{new_room_id}/report/{event_id}",
+            {"reason": "I'm not in this room but I have opinions anyways!"},
+            access_token=self.other_user_tok,
+        )
+
+        # The "other" user is not in the room, so their report should be rejected.
+        self.assertEqual(404, channel.code, msg=channel.result["body"])
+        self.assertEqual(
+            "Unable to report event: it does not exist or you aren't able to see it.",
+            channel.json_body["error"],
+            msg=channel.result["body"],
+        )
 
     def _assert_status(self, response_status: int, data: JsonDict) -> None:
         channel = self.make_request(