diff --git a/CHANGES.md b/CHANGES.md
index 5d4e80499e..dfdd8aa68a 100644
--- a/CHANGES.md
+++ b/CHANGES.md
@@ -1,3 +1,18 @@
+Synapse 1.21.0rc3 (2020-10-08)
+==============================
+
+Bugfixes
+--------
+
+- Fix duplication of events on high traffic servers, caused by PostgreSQL `could not serialize access due to concurrent update` errors. ([\#8456](https://github.com/matrix-org/synapse/issues/8456))
+
+
+Internal Changes
+----------------
+
+- Add Groovy Gorilla to the list of distributions we build `.deb`s for. ([\#8475](https://github.com/matrix-org/synapse/issues/8475))
+
+
 Synapse 1.21.0rc2 (2020-10-02)
 ==============================
 
diff --git a/README.rst b/README.rst
index e623cf863a..d609b4b62e 100644
--- a/README.rst
+++ b/README.rst
@@ -1,10 +1,6 @@
-================
-Synapse |shield|
-================
-
-.. |shield| image:: https://img.shields.io/matrix/synapse:matrix.org?label=support&logo=matrix
-  :alt: (get support on #synapse:matrix.org)
-  :target: https://matrix.to/#/#synapse:matrix.org
+=========================================================
+Synapse |support| |development| |license| |pypi| |python|
+=========================================================
 
 .. contents::
 
@@ -374,3 +370,23 @@ something like the following in their logs::
 
 This is normally caused by a misconfiguration in your reverse-proxy. See
 `<docs/reverse_proxy.md>`_ and double-check that your settings are correct.
+
+.. |support| image:: https://img.shields.io/matrix/synapse:matrix.org?label=support&logo=matrix
+  :alt: (get support on #synapse:matrix.org)
+  :target: https://matrix.to/#/#synapse:matrix.org
+
+.. |development| image:: https://img.shields.io/matrix/synapse-dev:matrix.org?label=development&logo=matrix
+  :alt: (discuss development on #synapse-dev:matrix.org)
+  :target: https://matrix.to/#/#synapse-dev:matrix.org
+
+.. |license| image:: https://img.shields.io/github/license/matrix-org/synapse
+  :alt: (check license in LICENSE file)
+  :target: LICENSE
+
+.. |pypi| image:: https://img.shields.io/pypi/v/matrix-synapse
+  :alt: (latest version released on PyPi)
+  :target: https://pypi.org/project/matrix-synapse
+
+.. |python| image:: https://img.shields.io/pypi/pyversions/matrix-synapse
+  :alt: (supported python versions)
+  :target: https://pypi.org/project/matrix-synapse
diff --git a/changelog.d/8456.misc b/changelog.d/8456.misc
deleted file mode 100644
index ccd260069b..0000000000
--- a/changelog.d/8456.misc
+++ /dev/null
@@ -1 +0,0 @@
-Reduce number of serialization errors of `MultiWriterIdGenerator._update_table`.
diff --git a/changelog.d/8475.misc b/changelog.d/8475.misc
deleted file mode 100644
index 69bcb04097..0000000000
--- a/changelog.d/8475.misc
+++ /dev/null
@@ -1 +0,0 @@
-Add Groovy Gorilla to the list of distributions we build `.deb`s for.
diff --git a/changelog.d/8492.misc b/changelog.d/8492.misc
new file mode 100644
index 0000000000..a344aee791
--- /dev/null
+++ b/changelog.d/8492.misc
@@ -0,0 +1 @@
+Clarify error message when plugin config parsers raise an error.
diff --git a/changelog.d/8493.doc b/changelog.d/8493.doc
new file mode 100644
index 0000000000..26797cd99e
--- /dev/null
+++ b/changelog.d/8493.doc
@@ -0,0 +1 @@
+Improve readme by adding new shield.io badges.
diff --git a/synapse/__init__.py b/synapse/__init__.py
index 500558bbdf..a86dc07ddc 100644
--- a/synapse/__init__.py
+++ b/synapse/__init__.py
@@ -48,7 +48,7 @@ try:
 except ImportError:
     pass
 
-__version__ = "1.21.0rc2"
+__version__ = "1.21.0rc3"
 
 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/util/module_loader.py b/synapse/util/module_loader.py
index bb62db4637..94b59afb38 100644
--- a/synapse/util/module_loader.py
+++ b/synapse/util/module_loader.py
@@ -36,7 +36,7 @@ def load_module(provider):
     try:
         provider_config = provider_class.parse_config(provider.get("config"))
     except Exception as e:
-        raise ConfigError("Failed to parse config for %r: %r" % (provider["module"], e))
+        raise ConfigError("Failed to parse config for %r: %s" % (provider["module"], e))
 
     return provider_class, provider_config