What this error means
The browser could not establish a valid TLS session with the server. The browser or proxy message describes the symptom, not necessarily the root cause. HostWithShery therefore checks the TLS, certificate and HTTPS 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.
- Port 443 returns non-TLS traffic — Test the hostname actually requested, its certificate dates and SAN coverage, and the TLS handshake. Root and www can serve different certificates.
- Broken TLS configuration — Test the hostname actually requested, its certificate dates and SAN coverage, and the TLS handshake. Root and www can serve different certificates.
- Unsupported protocol settings — Verify unsupported protocol settings 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.
- Port 443 returns non-TLS traffic — Test the hostname actually requested, its certificate dates and SAN coverage, and the TLS handshake. Root and www can serve different certificates.
- Broken TLS configuration — Test the hostname actually requested, its certificate dates and SAN coverage, and the TLS handshake. Root and www can serve different certificates.
- Unsupported protocol settings — Verify unsupported protocol settings from the public Internet and compare it with the value the responsible provider says should be live.
- Test the certificate/TLS endpoint — Test the hostname actually requested, its certificate dates and SAN coverage, and the TLS handshake. Root and www can serve different certificates.
- Confirm HTTPS service binding — Record the public status, final URL and relevant response headers. A working DNS answer does not prove that the application is serving a genuine website response.
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. Test the certificate/TLS endpoint. Confirm the public result after this step before making another unrelated change.
- 2. Confirm HTTPS service binding. Confirm the public result after this step before making another unrelated change.
- 3. Repair server TLS settings. Confirm the public result after this step before making another unrelated change.
How to confirm the repair
HTTPS should complete for the exact hostname, the certificate should be valid for that hostname, and root/www should follow the intended canonical redirect without a TLS error.
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.