diff --git a/changelog.d/19959.bugfix b/changelog.d/19959.bugfix
new file mode 100644
index 0000000000..5bca59c9b3
--- /dev/null
+++ b/changelog.d/19959.bugfix
@@ -0,0 +1 @@
+Don't 500 when calling /context on an out-of-band membership event.