NET::ERR_CERTIFICATE_TRANSPARENCY_REQUIRED — Fix

Enterno.io Editorial Team

ERR_CERTIFICATE_TRANSPARENCY_REQUIRED: Fix

By Anatoly Oshmanovsky · Updated Apr 18, 2026

Key idea:

NET::ERR_CERTIFICATE_TRANSPARENCY_REQUIRED — since October 2017 Chrome requires every public SSL cert to be logged in Certificate Transparency (CT). Cert without an SCT (Signed Certificate Timestamp) is rejected. Causes: issued before 2017, commercial CA did not submit to CT log, corporate proxy swapping cert. Fix: reissue via Let's Encrypt/DigiCert (all mainstream CAs write to CT automatically).

Below: causes, fixes, FAQ.

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Common Causes

Cert issued by a commercial CA not complying with CT policy (rare in 2026)
Corporate MITM proxy swapped the cert — private root without CT
Self-signed cert — no SCT by definition
Cert expired + renewed from cache without CT
Chromium flag CT enforcement enabled for the domain

Step-by-Step Fix

Reissue the cert via Let's Encrypt (SCT embedded automatically)
For commercial CAs confirm SCT embedded: openssl x509 -in cert.pem -text | grep -A1 SCT
If corporate — ask IT to add a CT-compliant root
Check cert in CT log: crt.sh
Temporary workaround (NOT production): chrome://flags/#chrome-root-store-cert-transparency-policy

Check SSL Certificate →

Related SSL Errors

CertificateExpiry, issuer, domains (SAN)

ChainIntermediate and root CA validation

TLS ProtocolTLS version and cipher suite

VulnerabilitiesHeartbleed, POODLE, weak ciphers

Why teams trust us

TLS 1.3

supported

Full

CA chain check

<2s

result

30/14/7

days-to-expiry alerts

How it works

Enter domain

TLS chain verified

Expiry date & vulnerabilities

What Does the SSL Check Cover?

SSL/TLS is the encryption protocol that protects data between the browser and server. Our tool analyzes the certificate, chain of trust, TLS version, and knownvulnerabilities.

Certificate Details

Issuer, validity period, signature algorithm, covered domains (SAN), and validation type (DV/OV/EV).

Chain of Trust

Full chain verification: from leaf certificate through intermediates to root CA.

TLS Analysis

Protocol version (TLS 1.2/1.3), cipher suites, Perfect Forward Secrecy (PFS) support.

Expiry Alerts

Set up a monitor — get Telegram and email alerts 30/14/7 days before expiration.

DV vs OV vs EV Certificates

DV (Domain Validation)

Confirms domain ownership only
Issued in minutes automatically
Free via Let's Encrypt
Suitable for most websites
Most common certificate type

OV / EV

Organization (OV) or Extended Validation (EV)
Issued in 1-5 business days
Costs $50 to $500/year
For finance, e-commerce, government sites
Increases user trust

Who uses this

DevOps

SSL certificate monitoring

Security

TLS config audit

SEO

HTTPS as ranking factor

E-commerce

customer trust

Common Mistakes

❌

Expired certificateBrowsers block sites with expired SSL. Set up auto-renewal or monitoring.

❌

Incomplete certificate chainWithout intermediate CA, some browsers and bots cannot verify the certificate.

❌

Mixed content on HTTPS siteHTTP resources on an HTTPS page — the browser lock icon disappears, reducing trust.

❌

Using TLS 1.0/1.1Legacy TLS versions have known vulnerabilities. Use TLS 1.2+ or 1.3.

❌

Domain mismatch in certificateThe certificate must cover all site domains, including www and subdomains.

Best Practices

✓

Set up auto-renewalLet's Encrypt + certbot with cron — certificate renews automatically every 60-90 days.

✓

Enable HSTSStrict-Transport-Security header forces browsers to always use HTTPS.

✓

Use TLS 1.3TLS 1.3 is faster (1-RTT handshake) and safer — legacy ciphers removed.

✓

Monitor expiration datesCreate a monitor on Enterno.io — get notified well before expiration.

✓

Verify chain after renewalAfter certificate renewal, confirm that intermediate certificates are installed.

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SSL certificate monitoring, check history and alerts 30 days before expiry.

Learn more

Research

TLS 1.3 Adoption 2026: Growth Pace

Errors

Frequently Asked Questions

What is SCT?

Signed Certificate Timestamp — cryptographic proof that the cert was logged in a public CT log (Google Argon, Cloudflare Nimbus, etc). Embedded in the cert extension, presented during TLS handshake, or stapled via OCSP.

Does Let's Encrypt include SCT?

Yes, automatically since 2018. The ISRG Root X1 cert has an SCT in the embedded CT extension.

How to verify SCT?

<a href="/en/ssl">Enterno SSL Checker</a> shows CT compliance in its report. Or <code>openssl x509 -in cert.pem -text | grep -A5 "SCT List"</code>.

Compliance impact?

CT compliance required by Chrome, Safari, Edge (Firefox not yet). Browser share ~85% — without SCT you lose most users.