diff --git a/.changeset/six-swans-taste.md b/.changeset/six-swans-taste.md
new file mode 100644
index 000000000..bcc6df0f6
--- /dev/null
+++ b/.changeset/six-swans-taste.md
@@ -0,0 +1,5 @@
+---
+"@xmtp/xmtp-js": patch
+---
+
+Add optional err to OnConnectionLostCallback