"User Session not found" sometimes happened when call OIDC User-Info API


We are using Keycloak 10.0.2 for our production microservices app. Each of the microservices is calling Keycloak’s OIDC user-info API to get some user’s information that cannot be shared within the access token claim. But many times (not always), it got “user session not found” error, even though the access token is still valid. The Keycloak replicas are set to 1 only.

Here is what the architecture looks like

Other microservices call the Keycloak directly via Kubernetes’s Services. No Gateway involved.

Why did this “User session not found” happened?
Is this related to the architecture?