--- title: "AppSync subscriptions: waiting for start_ack can still result in missing events" url: https://daily.dev/posts/appsync-subscriptions-waiting-for-start-ack-can-still-result-in-missing-events-uawvvrqix source_url: https://advancedweb.hu/shorts/appsync-subscriptions-waiting-for-start_ack-can-still-result-in-missing-events/ type: article source: "Advanced Web Machinery" published: 2025-12-18T18:47:56.716Z updated: 2026-08-24T06:56:44.558Z tags: ["aws", "graphql", "websocket"] reading_time: 3 upvotes: 0 comments: 0 language: en --- > ## Documentation Index > Fetch the complete documentation index at: https://daily.dev/llms.txt > Use this file to discover all available pages before exploring further. # AppSync subscriptions: waiting for start_ack can still result in missing events **[Advanced Web Machinery](https://daily.dev/sources/advancedweb)** · 3 min read · 0 upvotes · 0 comments ## Summary AppSync subscriptions may miss events even after receiving a start_ack confirmation. The start_ack message doesn't guarantee that all future events will be delivered, creating a temporal dead zone where updates can be lost. This breaks the common pattern of subscribing before querying current state to ensure no missed updates. The issue is particularly noticeable in tests and async workflows where subscriptions are created just before events occur. A bug report has been filed with AWS. ## Full article daily.dev links to this article rather than hosting it. Read it at the original source: ## Similar posts on daily.dev - [The Self-Cancelling Subscription](https://daily.dev/posts/the-self-cancelling-subscription-97xhpsdfu) · Lobsters · 3 upvotes · 0 comments --- Tags: [#aws](https://daily.dev/tags/aws), [#graphql](https://daily.dev/tags/graphql), [#websocket](https://daily.dev/tags/websocket) [View this post on daily.dev](https://daily.dev/posts/appsync-subscriptions-waiting-for-start-ack-can-still-result-in-missing-events-uawvvrqix)