Introduction

A platform migration can move application workloads successfully while the running service still reads credentials from the old vault or secret manager. Deployments may succeed, but the app continues using retired database passwords, expired API keys, or stale certificates because one secret reference, mounted path, or injection template still points at the previous secrets platform.

Treat this as a secret-source problem instead of a generic application outage. Start by checking where the running workload actually reads its secret values from, because secret migrations often update stored values in the new platform while the live application remains attached to the old one.

Symptoms

  • Applications fail after migration with credential or certificate errors
  • The new vault contains the correct secrets, but the running service still behaves as if old values are in use
  • One environment works while another still reads from the previous secret store
  • Rotating a secret in the new platform has no effect on the affected workload
  • Sidecars, injectors, or startup scripts still request data from the old vault
  • The issue started after moving secret storage, service identities, or workload injection tooling

Common Causes

  • The application still references the old secret path, namespace, mount, or vault URL
  • Injection templates, CSI drivers, or sidecar configuration still target the previous secret manager
  • A deployment variable or mounted file path overrides the intended new source
  • The workload identity or service account was migrated, but the live secret reference was not
  • Lease renewal, template rendering, or secret refresh still runs against the old platform
  • Validation confirmed the new vault held the right data but not that the running workload consumed it

Step-by-Step Fix

  1. Capture the failing workload state and record which secret path, file, or API endpoint it actually uses at runtime, because the live secret source matters more than the migration checklist.
  2. Compare that active secret reference with the intended post-migration vault or secret manager, because one stale path or endpoint can keep the service tied to retired credentials.
  3. Review deployment manifests, startup scripts, sidecar injector settings, and environment variables for references to the old vault, because secret sources often live across more than one layer.
  4. Check the workload identity, service account, or access policy tied to secret retrieval, because migrations sometimes move the vault endpoint while leaving the workload authorized only for the old platform.
  5. Update the authoritative secret reference and redeploy or reload the workload so the running process actually consumes the new source, because changing secret metadata alone does not rotate what is already mounted or cached.
  6. Confirm the application now reads the intended secret by testing the exact failing integration, because a healthy deployment does not prove the service stopped using old credentials.
  7. Verify the old vault no longer serves requests for the migrated workload, because silent fallback to the previous secret source can leave the problem partially hidden.
  8. Review related jobs, workers, and maintenance scripts if they also consume secrets independently, because migrations often fix the main app while secondary automation still uses the retired vault.
  9. Document secret ownership, injection method, and runtime validation steps for future migrations, because secret-source drift is hard to detect until credentials rotate or expire.