diff --git a/src/shrpx_http3_upstream.cc b/src/shrpx_http3_upstream.cc
index ac3399d7..c92f195c 100644
--- a/src/shrpx_http3_upstream.cc
+++ b/src/shrpx_http3_upstream.cc
@@ -984,15 +984,8 @@ int Http3Upstream::on_downstream_abort_request(Downstream *downstream,
 
 int Http3Upstream::on_downstream_abort_request_with_https_redirect(
     Downstream *downstream) {
-  int rv;
-
-  rv = redirect_to_https(downstream);
-  if (rv != 0) {
-    return -1;
-  }
-
-  handler_->signal_write();
-  return 0;
+  assert(0);
+  abort();
 }
 
 namespace {
@@ -1604,10 +1597,11 @@ int Http3Upstream::on_downstream_reset(Downstream *downstream, bool no_retry) {
 
 fail:
   if (rv == SHRPX_ERR_TLS_REQUIRED) {
-    rv = on_downstream_abort_request_with_https_redirect(downstream);
-  } else {
-    rv = on_downstream_abort_request(downstream, 502);
+    assert(0);
+    abort();
   }
+
+  rv = on_downstream_abort_request(downstream, 502);
   if (rv != 0) {
     shutdown_stream(downstream, NGHTTP3_H3_INTERNAL_ERROR);
   }
@@ -2318,10 +2312,11 @@ void Http3Upstream::initiate_downstream(Downstream *downstream) {
     auto dconn = handler_->get_downstream_connection(rv, downstream);
     if (!dconn) {
       if (rv == SHRPX_ERR_TLS_REQUIRED) {
-        rv = redirect_to_https(downstream);
-      } else {
-        rv = error_reply(downstream, 502);
+        assert(0);
+        abort();
       }
+
+      rv = error_reply(downstream, 502);
       if (rv != 0) {
         shutdown_stream(downstream, NGHTTP3_H3_INTERNAL_ERROR);
       }
@@ -2731,39 +2726,6 @@ int Http3Upstream::shutdown_stream_read(int64_t stream_id,
   return 0;
 }
 
-int Http3Upstream::redirect_to_https(Downstream *downstream) {
-  auto &req = downstream->request();
-  if (req.regular_connect_method() || req.scheme != "http") {
-    return error_reply(downstream, 400);
-  }
-
-  auto authority = util::extract_host(req.authority);
-  if (authority.empty()) {
-    return error_reply(downstream, 400);
-  }
-
-  auto &balloc = downstream->get_block_allocator();
-  auto config = get_config();
-  auto &httpconf = config->http;
-
-  StringRef loc;
-  if (httpconf.redirect_https_port == StringRef::from_lit("443")) {
-    loc = concat_string_ref(balloc, StringRef::from_lit("https://"), authority,
-                            req.path);
-  } else {
-    loc = concat_string_ref(balloc, StringRef::from_lit("https://"), authority,
-                            StringRef::from_lit(":"),
-                            httpconf.redirect_https_port, req.path);
-  }
-
-  auto &resp = downstream->response();
-  resp.http_status = 308;
-  resp.fs.add_header_token(StringRef::from_lit("location"), loc, false,
-                           http2::HD_LOCATION);
-
-  return send_reply(downstream, nullptr, 0);
-}
-
 void Http3Upstream::consume(int64_t stream_id, size_t nconsumed) {
   ngtcp2_conn_extend_max_stream_offset(conn_, stream_id, nconsumed);
   ngtcp2_conn_extend_max_offset(conn_, nconsumed);
diff --git a/src/shrpx_http3_upstream.h b/src/shrpx_http3_upstream.h
index 23874850..cc0d2353 100644
--- a/src/shrpx_http3_upstream.h
+++ b/src/shrpx_http3_upstream.h
@@ -120,7 +120,6 @@ public:
   void initiate_downstream(Downstream *downstream);
   int shutdown_stream(Downstream *downstream, uint64_t app_error_code);
   int shutdown_stream_read(int64_t stream_id, uint64_t app_error_code);
-  int redirect_to_https(Downstream *downstream);
   int http_stream_close(Downstream *downstream, uint64_t app_error_code);
   void consume(int64_t stream_id, size_t nconsumed);
   void remove_downstream(Downstream *downstream);