X_PWA_VAPID_KEY_MISSING
Means
no VAPID key pair for push
Typical cause
pwa.push is true and ULTIMATE_VAPID_PUBLIC_KEY / ULTIMATE_VAPID_PRIVATE_KEY are unset (or hold the published development pair) in a deployed environment — or one half is set without the other, anywhere. Refused at boot, before any service starts
Fix
x vapid create — seals a fresh pair into secrets.enc.json; or set both variables in the deployment's environment