Vault error during forwarded RPC request

Hello,

I'm having an issue with Vault.

I have a Vault instance installed in Cluster1 and an application running in Cluster2. My goal is to inject secrets from Vault into the application.

I already configured this successfully for an application running in the same cluster as Vault, and it works without any issues. However, when I try to do the same for an application running in a different Kubernetes cluster, it fails.

The following errors appear in the Vault logs:

2026-07-28T09:00:13.131Z [ERROR] core: forward request error: error="error during forwarding RPC request"
2026-07-28T09:00:13.131Z [ERROR] core: error during forwarded RPC request: error="rpc error: code = Canceled desc = context canceled"

Has anyone encountered this issue before or knows what could be causing it?

Start by reproducing the Vault-to-application setup across Cluster1 and Cluster2, then inspect the Vault logs around the forwarded RPC request and the context-canceled error. Compare the working same-cluster configuration with the failing cross-cluster configuration; done means identifying the cross-cluster cause and documenting or implementing a verified fix.

Written by the indexing model from the issue text.