What this error means
Meta Facebook Login can show this message when the page hosting the JavaScript SDK is not included in the app configuration allowed for JavaScript SDK login. This is an application configuration error, not a generic DNS failure. The browser or proxy message describes the symptom, not necessarily the root cause. HostWithShery therefore checks the application host configuration evidence that can be observed publicly before recommending a configuration change.
Most likely causes
These are the first explanations to test because each can produce this exact symptom. Treat them as hypotheses until the matching public evidence is present.
- Current production hostname is absent from the Facebook Login JavaScript SDK host list — Verify current production hostname is absent from the Facebook Login JavaScript SDK host list from the public Internet and compare it with the value the responsible provider says should be live.
- Www, apex, staging or alternate hostname differs from the configured host — Verify www, apex, staging or alternate hostname differs from the configured host from the public Internet and compare it with the value the responsible provider says should be live.
- Application moved domains without updating Meta app settings — Verify application moved domains without updating Meta app settings from the public Internet and compare it with the value the responsible provider says should be live.
- The page is using a different Meta app than expected — Verify the page is using a different Meta app than expected from the public Internet and compare it with the value the responsible provider says should be live.
What to check on your domain
Use the embedded scan to compare the failing layer with adjacent layers that can produce the same visible error. This prevents a DNS change from being used to “fix” a TLS problem, or an SSL-mode change from masking an origin failure.
- Current production hostname is absent from the Facebook Login JavaScript SDK host list — Verify current production hostname is absent from the Facebook Login JavaScript SDK host list from the public Internet and compare it with the value the responsible provider says should be live.
- Www, apex, staging or alternate hostname differs from the configured host — Verify www, apex, staging or alternate hostname differs from the configured host from the public Internet and compare it with the value the responsible provider says should be live.
- Application moved domains without updating Meta app settings — Verify application moved domains without updating Meta app settings from the public Internet and compare it with the value the responsible provider says should be live.
- The page is using a different Meta app than expected — Verify the page is using a different Meta app than expected from the public Internet and compare it with the value the responsible provider says should be live.
- Confirm the exact browser hostname and Meta app ID — Verify confirm the exact browser hostname and Meta app ID from the public Internet and compare it with the value the responsible provider says should be live.
Fixes in the recommended order
Change the smallest confirmed layer first. Preserve working DNS and mail records, document the current value, apply one repair, and then retest before moving to the next possibility.
- 1. Confirm the exact browser hostname and Meta app ID. Confirm the public result after this step before making another unrelated change.
- 2. Add the intended host in the app Facebook Login JavaScript SDK settings. Confirm the public result after this step before making another unrelated change.
- 3. Remove accidental staging/old-host references from production. Confirm the public result after this step before making another unrelated change.
- 4. Retest login on the exact HTTPS hostname. Confirm the public result after this step before making another unrelated change.
What the live public check can and cannot verify
The embedded public check can confirm whether the hostname itself resolves and serves a website. It cannot read private Meta app settings. If the public hostname is healthy, verify the exact browser hostname and app ID inside the current Meta Facebook Login configuration; do not change DNS merely to clear an application allowlist error.
Common production mismatch
Treat the apex domain, www hostname, staging hostname and alternate login host as distinct values. A login flow can work on one host and fail on another when the JavaScript SDK configuration does not include the hostname actually serving the page.
How to confirm the repair
The same public test that exposed the problem should now return a healthy result, without creating a new DNS, TLS, mail or redirect regression.
If the error remains
Capture the checked hostname, exact timestamp, final DNS addresses, redirect/TLS result and the failing public status before escalating. That evidence gives a hosting or provider support team something testable instead of only the browser message. If results differ by resolver or network, include those differences rather than assuming the failure is universal.
What not to change
Do not replace nameservers, delete unrelated mail records, disable security controls, remove IPv6 blindly or purge the entire configuration merely because this message appears. Diagnose the failing layer first; broad changes can turn one isolated fault into several independent faults.
Technical references
These primary standards and provider documents are used to verify the behavior described on this page. Provider dashboards can change, so use the current official value for tenant-specific DNS records rather than copying an example from another account.