diff --git a/scripts/ci/sandboxed_web_e2e.py b/scripts/ci/sandboxed_web_e2e.py
index 682202fa..506cc044 100644
--- a/scripts/ci/sandboxed_web_e2e.py
+++ b/scripts/ci/sandboxed_web_e2e.py
@@ -26,14 +26,12 @@
 RESULT_MARKER = "SANDBOXED_WEB_E2E_RESULT"
 
 
-class NoRedirectHandler(urllib.request.HTTPErrorProcessor):
+class NoRedirectHandler(urllib.request.HTTPRedirectHandler):
     """Explicitly disable redirects to prevent SSRF bypasses via 301/302 to local IPs."""
 
-    def http_response(self, request, response):
-        """Return the original HTTP response without following redirects."""
-        return response
-
-    https_response = http_response
+    def redirect_request(self, req, fp, code, msg, headers, newurl):
+        """Raise an HTTPError instead of following the redirect."""
+        raise urllib.error.HTTPError(req.full_url, code, msg, headers, fp)
 
 
 @dataclass
diff --git a/tests/test_sandboxed_web_e2e.py b/tests/test_sandboxed_web_e2e.py
index 38f5f8bf..7bd9a2a8 100644
--- a/tests/test_sandboxed_web_e2e.py
+++ b/tests/test_sandboxed_web_e2e.py
@@ -228,16 +228,16 @@ def open(self, url, timeout):
     assert sandboxed_web_e2e.tail_text(log_path).splitlines()[0] == "line-10"
 
 
-def test_no_redirect_handler_returns_redirect_without_following():
-    """Readiness checks must not follow redirects to attacker-controlled internal URLs."""
-
-    class RedirectResponse:
-        status = 302
+def test_no_redirect_handler_raises_httperror_without_following():
+    """Readiness checks must raise HTTPError on redirects to prevent attacker-controlled internal URLs."""
+    import urllib.error
 
     request = sandboxed_web_e2e.urllib.request.Request("https://example.test/ready")
-    response = RedirectResponse()
 
-    assert sandboxed_web_e2e.NoRedirectHandler().http_response(request, response) is response
+    with pytest.raises(urllib.error.HTTPError) as exc_info:
+        sandboxed_web_e2e.NoRedirectHandler().redirect_request(request, None, 302, "Found", {}, "http://127.0.0.1")
+
+    assert exc_info.value.code == 302
 
 
 def test_wait_for_url_returns_false_after_timeout(monkeypatch, tmp_path):