ERR_CERTIFICATE_TRANSPARENCY_REQUIRED: Fix

• 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

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

Check SSL Certificate →

• ERR_SSL_PROTOCOL_ERROR
• NET::ERR_CERT_AUTHORITY_INVALID
• SSL Handshake Failed
• All SSL errors

To resolve the NET::ERR_CERTIFICATE_TRANSPARENCY_REQUIRED error, ensure that your SSL/TLS certificate complies with Certificate Transparency (CT) requirements. This involves using a certificate from a Certificate Authority (CA) that has logged the certificate in public CT logs. Validate your certificate using tools like crt.sh and consider reissuing it if it’s not logged. Additionally, ensure your server is configured to send the appropriate CT information.

Certificate Transparency (CT) is a security standard designed to prevent the issuance of fraudulent SSL/TLS certificates. As of 2018, major browsers like Chrome and Firefox enforce CT logs for certificates issued by recognized Certificate Authorities (CAs). This means that when your website's SSL certificate is issued, it must be publicly logged in a CT log to be trusted by browsers. Failing to meet these requirements will result in users encountering the NET::ERR_CERTIFICATE_TRANSPARENCY_REQUIRED error.

To comply with CT, follow these steps:

• Select a Trusted Certificate Authority: Choose a CA that supports Certificate Transparency. Examples include Let's Encrypt, DigiCert, and GlobalSign.
• Request Certificate Logging: When applying for an SSL certificate, ensure that your CA includes the necessary CT log entries.
• Verify CT Logging: Use tools like Certificate Transparency logs to check if your certificate is logged correctly.

By adhering to these requirements, you can avoid the NET::ERR_CERTIFICATE_TRANSPARENCY_REQUIRED error and enhance your website's security.

To effectively address the NET::ERR_CERTIFICATE_TRANSPARENCY_REQUIRED error, follow these practical steps:

1. Check Your SSL Certificate: Run the following command to inspect your certificate:

openssl s_client -connect yourdomain.com:443 -servername yourdomain.com

This command will display your certificate details. Look for the Certificate chain section.

1. Verify Certificate Logging: Use crt.sh to check if your certificate is logged. Enter your domain name, and ensure that your certificate appears in the search results.
2. Reissue Your Certificate: If your certificate is not logged, contact your CA to reissue it with the necessary CT log entries. Specify that you require CT compliance.
3. Configure Your Web Server: Ensure your web server is correctly set up to provide the CT information. For example, if you are using Apache, add the following directives to your configuration file:

SSLUseStapling On
SSLStaplingCache "shmcb:/var/run/ssl_stapling(128000)"

These configurations will help enable OCSP Stapling, which can assist in ensuring your certificate is compliant with CT.

1. Test Your Configuration: After reissuing and configuring your SSL certificate, test your site using tools like SSL Labs. This will confirm that your SSL certificate is properly set up and logged.
2. Monitor for Errors: Regularly check your site for SSL errors and ensure that your certificate remains compliant with CT requirements.

By following these practical steps, you can effectively fix the NET::ERR_CERTIFICATE_TRANSPARENCY_REQUIRED error and maintain a secure browsing experience for your users.