A Gravity Forms API error saying credentials were not found is not the same as an invalid secret. The client may have sent authentication that never reached PHP, or it may have followed a redirect to a different endpoint. Verify where the header disappears before rotating every key or weakening the firewall.
Classify the response at the right layer
Capture the HTTP status, response content type, sanitized error code and request time. An HTML login page or managed challenge is different from a Gravity Forms JSON authentication response. Use the WAF integration guide when the request is blocked before WordPress.
Gravity Forms' authentication documentation distinguishes missing credentials, invalid secrets and permission failures. Match the actual log message instead of assuming every 401 has the same repair. Confirm that REST API access is enabled and that you are using the intended authentication method.
Check the final HTTPS endpoint
Inspect redirects without attaching credentials first:
curl -sS -I --max-time 15 https://example.com/wp-json/gf/v2/forms
Replace the example with the authorized site's endpoint. A HEAD response helps inspect routing but does not substitute for the authenticated method your integration needs. Record any Location header and verify the destination hostname before sending secrets.
Configure the integration to call the final canonical HTTPS endpoint directly where supported. Do not enable unrestricted credential forwarding across redirects. A host change from www to apex, a staging URL or an HTTP-to-HTTPS redirect deserves explicit review rather than a blanket follow-all setting.
Routing: Use intended final endpoint. Logs: Never record raw secrets. Valid request: Expected JSON returned. Invalid request: Still rejected. Explanatory checklist, not a customer test result.
Ask the host to check header presence, not its value
Use a dedicated, least-privileged test credential stored in the integration's secret facility. Ask the host to confirm whether the Authorization header is present at the proxy and PHP boundaries for a single timestamped request. Support logs should contain a presence indicator, not the header's contents.
Gravity Forms documents hosting configurations that fail to pass Basic authentication to PHP and points hosts to Apache's CGIPassAuth directive. That is a host-specific diagnosis, not a reason to paste Apache rules into Nginx or broadly expose server variables. Have the responsible operator apply the correct configuration for the stack.
Keep authentication and authorization separate
After header delivery is restored, the request may still fail because the credential lacks read access or the associated user lacks the endpoint's capability. The forms endpoint documentation lists its required capability. Grant only what the intended integration requires, not administrator access to silence an error.
Retest one authorized read from the integration's real host and one deliberately invalid credential. The first should return the intended JSON data; the second should remain rejected. Keep rate limits and unrelated WAF rules in place.
Remove temporary logging and revoke disposable test credentials after the diagnosis. HandL WP can trace a failing form integration using endpoint, timestamp and redacted error evidence without collecting customer entries or full authentication headers.
References reviewed October 12, 2026. Examples are explanatory, not customer test results.