Connection Issues with Redis Cluster on

I have an application deployed across three regions (IAD, MIA, and LAX) on In addition, I have set up an Upstash Redis cluster with the primary region in IAD and read replicas in LAX and MIA.

Recently, I’ve been experiencing continuous crashes of the application in the IAD region. The error message states, “failed to connect to redis dial tcp: lookup on [fdaa::3]:53: no such host.”

However, I can use fly redis connect to access the Redis cluster, which seems to be healthy. Additionally, the application instances in MIA and LAX have no issues connecting to the Redis cluster.

I am seeking help in identifying the cause of this issue and any potential solutions. Any ideas or suggestions are greatly appreciated.

We’ve seen other reports of this failure but unfortunately there’s no concrete resolution as all the components seem to be working as expected.

We are able to resolve the hostname from host running your app, so redeploy your app and see if the issue still persists. It could have been a temporary issue with dns resolution.

The issue is now resolved. Thank you.

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