Pusher outage: Elevated API Errors in AP4 Cluster

Affected components

• Channels REST API
• Channels Stats Integrations
• Channels WebSocket client API

1. postmortemOct 23, 2025, 14:12 UTC

   ## **Root Cause Analysis: Elevated API Errors and Outage in AP4 Cluster** **Incident Date:** October 20, 2025 **Status:** Resolved ### **Summary** Between **October 20 and October 21, 2025**, customers using the **AP4 cluster** experienced elevated API errors, latency, and message publishing failures. The issue primarily affected the **Channels API**, preventing customers from publishing new messages and leading to degraded real-time functionality for end-users. During system recovery and while implementing mitigations from a previous incident on Oct 18th, a **misconfigured Redis container** in the AP4 cluster failed to start correctly, preventing caching operations needed for API requests. This misconfiguration went undetected by proactive monitoring, delaying full recovery until October 21 at 17:43 UTC. ### **Impact** Throughout the incident period, customers in the **AP4 cluster** experienced: * **High API error rates** when attempting to publish messages through the Channel

2. resolvedOct 21, 2025, 17:43 UTC

   This incident has been resolved.

3. monitoringOct 21, 2025, 17:39 UTC

   A fix has been implemented and we are monitoring the results.

4. identifiedOct 21, 2025, 17:32 UTC

   We are currently investigating an issue affecting the Channels API. A large number of customers may be unable to publish new messages through the API in the AP4 cluster.

5. monitoringOct 21, 2025, 15:29 UTC

   A fix has been implemented and we are monitoring. The cluster will take a few more minutes to fully stabilize across all nodes.

6. identifiedOct 21, 2025, 15:27 UTC

   The team continues to make progress restoring the cache services. We anticipate full resolution in the next 10-15 minutes.

7. identifiedOct 21, 2025, 15:09 UTC

   The team has identified the issue with one of our backend caching servers. The team is working to restore the connections to the server.

8. investigatingOct 21, 2025, 15:06 UTC

   We're experiencing an elevated level of API errors and latency in AP4 and are currently looking into the issue.

What APIStatus.watch saw

Our 5-minute checks didn't record a change in Pusher's overall status around this incident. Smaller or regional incidents often leave a provider's overall status green.

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How often does Pusher have incidents?

Pusher reported 0 incidents in the last 90 days. See Pusher's uptime and incident history