diff --git a/.scripts/update_refs.sh b/.scripts/update_refs.sh
index 6b2f57b2..c17daf29 100755
--- a/.scripts/update_refs.sh
+++ b/.scripts/update_refs.sh
@@ -80,7 +80,7 @@ echo "$MESSAGE"
 # shellcheck disable=SC2016 # We intentionally don't want to expand the variable.
 find demos stacks -type f \
   -exec grep --color=always -l githubusercontent {} \; \
-  -exec sed -i -E 's#(stackabletech/demos)/main/#\1/\${UPDATE_BRANCH_REF}/#' {} \; \
+  -exec sed -i -E 's#(stackabletech/demos)/(refs/heads/)?main/#\1/\${UPDATE_BRANCH_REF}/#' {} \; \
 | prepend "\t"
 
 # Now, for all modified files, we can use envsubst
diff --git a/demos/signal-processing/create-nifi-ingestion-job.yaml b/demos/signal-processing/create-nifi-ingestion-job.yaml
index dd67cedf..45d75ff1 100644
--- a/demos/signal-processing/create-nifi-ingestion-job.yaml
+++ b/demos/signal-processing/create-nifi-ingestion-job.yaml
@@ -87,12 +87,14 @@ data:
     service_login(username=USERNAME, password=PASSWORD)
     print("Logged in")
 
-    # This file path needs adjustment for versioned demos on release branch
-    response = requests.get("https://raw.githubusercontent.com/stackabletech/demos/refs/heads/main/demos/signal-processing/DownloadAndWriteToDB.json")
+    # At release time, .scripts/update_refs.sh rewrites the branch in this URL to the release
+    # branch. Keep the URL in a form its regex matches, or release-branch installs will
+    # download this file from main (see the 26.3 regression).
+    response = requests.get("https://raw.githubusercontent.com/stackabletech/demos/main/demos/signal-processing/DownloadAndWriteToDB.json")
 
     filename = "/tmp/DownloadAndWriteToDB.json"
-    with open(filename, "wb") as f:
-        f.write(response.content)
+    with open(filename, "w") as f:
+        f.write(response.text.replace("{{ NAMESPACE }}", os.environ["NAMESPACE"]))
 
     pg_id = get_root_pg_id()