diff --git a/lib/cwmp.ts b/lib/cwmp.ts
index 0e9584b..b28e046 100644
--- a/lib/cwmp.ts
+++ b/lib/cwmp.ts
@@ -1211,12 +1211,17 @@ export function listener(
     })
     .catch((err) => {
       currentSessions.delete(httpResponse.connection);
-      httpResponse.writeHead(500, { Connection: "close" });
-      httpResponse.end(`${err.name}: ${err.message}`);
       stats.concurrentRequests -= 1;
       setTimeout(() => {
         throw err;
       });
+      try {
+        httpResponse.connection.unref();
+        httpResponse.writeHead(500, { Connection: "close" });
+        httpResponse.end(`${err.name}: ${err.message}`);
+      } catch (err) {
+        // Ignore
+      }
     });
 }
 
diff --git a/lib/ui.ts b/lib/ui.ts
index 759454c..0e2192c 100644
--- a/lib/ui.ts
+++ b/lib/ui.ts
@@ -60,7 +60,9 @@ const getAuthorizer = memoize(
 );
 
 koa.on("error", async (err) => {
-  throw err;
+  setTimeout(() => {
+    throw err;
+  });
 });
 
 koa.use(async (ctx, next) => {