diff --git a/.changeset/neat-walls-buy.md b/.changeset/neat-walls-buy.md
new file mode 100644
index 000000000000..1c55f7e22e2b
--- /dev/null
+++ b/.changeset/neat-walls-buy.md
@@ -0,0 +1,5 @@
+---
+'@sveltejs/kit': patch
+---
+
+Pass along custom properties added to Error
diff --git a/packages/kit/src/runtime/server/page/render.js b/packages/kit/src/runtime/server/page/render.js
index 6e0f10f47a31..5226a337737c 100644
--- a/packages/kit/src/runtime/server/page/render.js
+++ b/packages/kit/src/runtime/server/page/render.js
@@ -215,8 +215,8 @@ function serialize_error(error) {
 	if (!error) return null;
 	let serialized = try_serialize(error);
 	if (!serialized) {
-		const { name, message, stack, frame, loc } = error;
-		serialized = try_serialize({ name, message, stack, frame, loc });
+		const { name, message, stack } = error;
+		serialized = try_serialize({ ...error, name, message, stack });
 	}
 	if (!serialized) {
 		serialized = '{}';