diff --git a/changelog.d/10157.bugfix b/changelog.d/10157.bugfix
new file mode 100644
index 000000000000..6eaaa05b808c
--- /dev/null
+++ b/changelog.d/10157.bugfix
@@ -0,0 +1 @@
+Fix a bug introduced in v1.21.0 which could cause `/sync` to return immediately with an empty response.
diff --git a/changelog.d/10157.misc b/changelog.d/10157.misc
deleted file mode 100644
index 6c1d0e6e5933..000000000000
--- a/changelog.d/10157.misc
+++ /dev/null
@@ -1 +0,0 @@
-Extend `ResponseCache` to pass a context object into the callback.
diff --git a/changelog.d/10158.bugfix b/changelog.d/10158.bugfix
new file mode 100644
index 000000000000..6eaaa05b808c
--- /dev/null
+++ b/changelog.d/10158.bugfix
@@ -0,0 +1 @@
+Fix a bug introduced in v1.21.0 which could cause `/sync` to return immediately with an empty response.