# Error Handling and Troubleshooting

Common responses and fixes:

* 401 Invalid access token
  * Missing/invalid `Authorization: Bearer <JWT>` header
  * Disallowed `alg` (only RS256/ES256)
  * Missing `sub`
  * Expired token → header includes `WWW-Authenticate: Bearer error="expired_token"`
  * `JWT_PROVIDER_PUBLIC_KEY` misconfigured (must be Base64 DER SPKI)
* 400 Flow init failed
  * QR content is not supported by the server you pointed to
  * Verifier/issuer returned a 4xx → message surfaced in `data.errorMessage`
* 404 Process not found
  * Wrong or expired `processId`
  * Confirm called by a different user than the one who initiated
* 422 Proof verification failed (credential import)
  * VC proof invalid or schema missing/mismatched
* 400 Credential subject mismatch
  * Subject DID differs from holder DID and `allowForeignSubject=false`
* Database connection errors
  * Verify `DB_*` values and connectivity; run migrations
* did:web configuration errors
  * Ensure `DID_WEB_DOMAIN` is set
  * If `DID_WEB_PORT` is set, it must be numeric

Tips:

* Use `/health/liveness` and `/health/readiness` to check service and DB
* Use debug endpoints locally to generate a working token quickly


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