QStash Service Disruption in the EU Region

Final update

## What happened A configuration change applied to QStash's EU networking layer introduced an outbound connectivity fault. Between **09:11 and 09:45 UTC**, a subset of QStash instances had degraded egress connectivity, and some dispatched messages may have failed on their initial attempt. A related side effect caused some servers to egress from IP addresses outside QStash's advertised outbound range until **11:24 UTC**; during that window, endpoints enforcing QStash IP allowlists may have rejected requests from those servers. QStash's automatic retries delivered many affected messages on subsequent attempts once connectivity was restored, and QStash is now operating normally. ## Customer impact Impact was limited to the EU region and to two effects within the window above: * **Delivery delays / failures** _\(09:11 – 09:45 UTC\)_ , messages dispatched through affected instances may have failed on their first attempt. Thanks to automatic retries with backoff, most were re-delivered once connectivity recovered; messages that exhausted their retry policy during the window followed their configured failure path \(e.g., DLQ / failure callback\). * **Allowlist rejections** _\(09:11 – 11:

1. Postmortem · Jun 19, 13:52 UTC
   ## What happened A configuration change applied to QStash's EU networking layer introduced an outbound connectivity fault. Between **09:11 and 09:45 UTC**, a subset of QStash instances had degraded egress connectivity, and some dispatched messages may have failed on their initial attempt. A related side effect caused some servers to egress from IP addresses outside QStash's advertised outbound range until **11:24 UTC**; during that window, endpoints enforcing QStash IP allowlists may have rejected requests from those servers. QStash's automatic retries delivered many affected messages on subsequent attempts once connectivity was restored, and QStash is now operating normally. ## Customer impact Impact was limited to the EU region and to two effects within the window above: * **Delivery delays / failures** _\(09:11 – 09:45 UTC\)_ , messages dispatched through affected instances may have failed on their first attempt. Thanks to automatic retries with backoff, most were re-delivered once connectivity recovered; messages that exhausted their retry policy during the window followed their configured failure path \(e.g., DLQ / failure callback\). * **Allowlist rejections** _\(09:11 – 11:24 UTC\)_ , customers who restrict inbound traffic to QStash's outbound IP ranges may have seen requests from the affected servers rejected. Customers who do not enforce source-IP allowlisting were unaffected by this. ## Root cause A routine networking configuration change contained an error that:
2. Resolved · Jun 19, 09:11 UTC
   We identified an outbound networking issue affecting a subset of QStash server instances in the EU region between 2026-06-19 09:11 UTC and 2026-06-19 09:45 UTC. During this period, some requests dispatched by QStash may have failed. The issue has been resolved, and QStash is currently operating normally. We will publish a postmortem with additional details as soon as it is available. Update: We identified that one QStash server had been assigned an outbound IP address outside of the configured QStash IP range. This remained the case until 2026-06-19 11:24 UTC. Endpoints that restrict access based on QStash outbound IP allowlists may have rejected requests from this server during this period.