diff --git a/CHANGES.md b/CHANGES.md
index 7ce28c4c182a17013cdf4272a82c4b814384199e..62ea684e586a2d76fcaac9cf60a82a0da62cc962 100644
--- a/CHANGES.md
+++ b/CHANGES.md
@@ -1,3 +1,19 @@
+Synapse 1.40.0rc2 (2021-08-04)
+==============================
+
+Bugfixes
+--------
+
+- Fix the `PeriodicallyFlushingMemoryHandler` inhibiting application shutdown because of its background thread. ([\#10517](https://github.com/matrix-org/synapse/issues/10517))
+- Fix a bug introduced in Synapse v1.40.0rc1 that could cause Synapse to respond with an error when clients would update read receipts. ([\#10531](https://github.com/matrix-org/synapse/issues/10531))
+
+
+Internal Changes
+----------------
+
+- Fix release script to open the correct URL for the release. ([\#10516](https://github.com/matrix-org/synapse/issues/10516))
+
+
 Synapse 1.40.0rc1 (2021-08-03)
 ==============================
 
diff --git a/debian/changelog b/debian/changelog
index 45df5c170b835d240062c6a928487d1493e4385e..39d9c8169e0974091474aade9ff759d388cc947b 100644
--- a/debian/changelog
+++ b/debian/changelog
@@ -1,3 +1,9 @@
+matrix-synapse-py3 (1.40.0~rc2) stable; urgency=medium
+
+  * New synapse release 1.40.0~rc2.
+
+ -- Synapse Packaging team <packages@matrix.org>  Wed, 04 Aug 2021 17:08:55 +0100
+
 matrix-synapse-py3 (1.40.0~rc1) stable; urgency=medium
 
   [ Richard van der Hoff ]
diff --git a/scripts-dev/release.py b/scripts-dev/release.py
index e864dc6ed53f1d75baa7c1314d41e5924247bc8f..a339260c437196403a86435bf81c25f28bb1f1e1 100755
--- a/scripts-dev/release.py
+++ b/scripts-dev/release.py
@@ -305,7 +305,7 @@ def tag(gh_token: Optional[str]):
     )
 
     # Open the release and the actions where we are building the assets.
-    click.launch(release.url)
+    click.launch(release.html_url)
     click.launch(
         f"https://github.com/matrix-org/synapse/actions?query=branch%3A{tag_name}"
     )
diff --git a/synapse/__init__.py b/synapse/__init__.py
index d6c176550897105fbe2a61e0a8193213afb9f69a..da524635316283fcb319e32e614d0ce416344a38 100644
--- a/synapse/__init__.py
+++ b/synapse/__init__.py
@@ -47,7 +47,7 @@ try:
 except ImportError:
     pass
 
-__version__ = "1.40.0rc1"
+__version__ = "1.40.0rc2"
 
 if bool(os.environ.get("SYNAPSE_TEST_PATCH_LOG_CONTEXTS", False)):
     # We import here so that we don't have to install a bunch of deps when
diff --git a/synapse/logging/handlers.py b/synapse/logging/handlers.py
index a6c212f300fd18f009119981e665203e6cb5e93b..af5fc407a8e5e1445db74a921fc06dba4df99437 100644
--- a/synapse/logging/handlers.py
+++ b/synapse/logging/handlers.py
@@ -45,6 +45,7 @@ class PeriodicallyFlushingMemoryHandler(MemoryHandler):
         self._flushing_thread: Thread = Thread(
             name="PeriodicallyFlushingMemoryHandler flushing thread",
             target=self._flush_periodically,
+            daemon=True,
         )
         self._flushing_thread.start()
 
diff --git a/synapse/rest/client/v2_alpha/receipts.py b/synapse/rest/client/v2_alpha/receipts.py
index 4b98979b477d1865f3302292daf79001ba42be76..d9ab836cd892a62ae667c3fe3129ebdb294f6402 100644
--- a/synapse/rest/client/v2_alpha/receipts.py
+++ b/synapse/rest/client/v2_alpha/receipts.py
@@ -43,7 +43,7 @@ class ReceiptRestServlet(RestServlet):
         if receipt_type != "m.read":
             raise SynapseError(400, "Receipt type must be 'm.read'")
 
-        body = parse_json_object_from_request(request)
+        body = parse_json_object_from_request(request, allow_empty_body=True)
         hidden = body.get(ReadReceiptEventFields.MSC2285_HIDDEN, False)
 
         if not isinstance(hidden, bool):
diff --git a/tests/rest/client/v2_alpha/test_sync.py b/tests/rest/client/v2_alpha/test_sync.py
index f6ae9ae18110e7b31627054883d84e2d4f2ccfc5..15748ed4fd9f7eba90bca6daa0b27e27201d2911 100644
--- a/tests/rest/client/v2_alpha/test_sync.py
+++ b/tests/rest/client/v2_alpha/test_sync.py
@@ -418,6 +418,18 @@ class ReadReceiptsTestCase(unittest.HomeserverTestCase):
         # Test that the first user can't see the other user's hidden read receipt
         self.assertEqual(self._get_read_receipt(), None)
 
+    def test_read_receipt_with_empty_body(self):
+        # Send a message as the first user
+        res = self.helper.send(self.room_id, body="hello", tok=self.tok)
+
+        # Send a read receipt for this message with an empty body
+        channel = self.make_request(
+            "POST",
+            "/rooms/%s/receipt/m.read/%s" % (self.room_id, res["event_id"]),
+            access_token=self.tok2,
+        )
+        self.assertEqual(channel.code, 200)
+
     def _get_read_receipt(self):
         """Syncs and returns the read receipt."""