API Gateway is a Kubernetes controller, which operates on APIRule custom resources (CRs). To diagnose problems, inspect the status code of the APIRule CR:

kubectl describe apirules.gateway.kyma-project.io -n {NAMESPACE} {APIRULE_NAME}

If the status is Error, edit the APIRule and fix the issues described in the .Status.APIRuleStatus.desc field. If you still encounter issues, make sure that API Gateway, Hydra, and Oathkeeper are running, or take a look at one of the more specific troubleshooting guides:

• Cannot connect to a service exposed by an APIRule - 401 Unauthorized or 403 Forbidden
• Cannot connect to a service exposed by an APIRule - 404 Not Found
• Cannot connect to a service exposed by an APIRule - 500 Internal Server Error