diff --git a/.changeset/few-waves-dream.md b/.changeset/few-waves-dream.md
new file mode 100644
index 0000000000..72123171b8
--- /dev/null
+++ b/.changeset/few-waves-dream.md
@@ -0,0 +1,5 @@
+---
+'@backstage/backend-common': patch
+---
+
+AWSS3UrlReader now throws a `NotModifiedError` (exported from @backstage/backend-common) when s3 returns a 304 response.