ERR_CERT_WEAK_SIGNATURE_ALGORITHM: Obsolete SHA-1/MD5

ERR_CERT_WEAK_SIGNATURE_ALGORITHM means the SSL certificate is signed with an obsolete algorithm (SHA-1, MD5, MD2). Chrome blocks such certificates since 2017. Fix: reissue with SHA-256 or stronger. All modern CAs (Let's Encrypt, DigiCert) default to SHA-256.

The error can appear in Chrome, Edge, Opera, Brave (all Chromium-based), and partially in Firefox and Safari. Different browsers display the same code differently, but the underlying issue is the same.

1. Check the SSL certificate online — the Enterno.io checker shows the grade, expiry, chain, and specific cause.
2. If the issue is server-side — reissue the certificate via certbot or your chosen CA.
3. Update nginx/apache config (enable TLS 1.2/1.3, fullchain, correct ciphers).
4. Check kernel OpenSSL — an outdated openssl < 1.1 can break handshakes.
5. After deploy: recheck via SSL checker + clear the browser SSL cache.

Check SSL now →

• NET::ERR_CERT_AUTHORITY_INVALID
• ERR_CERT_DATE_INVALID
• ERR_SSL_PROTOCOL_ERROR
• Mixed Content
• Check SSL certificate online →

The ERR_CERT_WEAK_SIGNATURE_ALGORITHM error indicates that the SSL certificate uses a cryptographic signature algorithm deemed insecure, such as SHA-1. To resolve this issue, update your SSL certificate to use a stronger signature algorithm like SHA-256 or SHA-384. Ensure your server configuration supports these algorithms and consider obtaining a new certificate from a trusted Certificate Authority (CA) that complies with current security standards.

The ERR_CERT_WEAK_SIGNATURE_ALGORITHM error occurs when a web browser, such as Chrome or Firefox, encounters an SSL certificate that employs a weak signature algorithm. This typically involves algorithms like SHA-1, which have been deprecated due to vulnerabilities that make them susceptible to attacks. As of 2026, modern web standards require the use of stronger algorithms like SHA-256 or SHA-384 to ensure secure communications.

This error can lead to significant issues, including warnings in the browser that discourage users from proceeding to the website. Therefore, it is essential for web administrators and developers to rectify this error promptly to maintain the integrity and security of their sites.

To identify if your SSL certificate is using a weak signature algorithm, you can utilize online SSL checkers or commands such as:

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

In the output, look for the line that starts with Signature Algorithm:. If it mentions SHA-1 or another weak algorithm, an update is necessary.

To fix the ERR_CERT_WEAK_SIGNATURE_ALGORITHM error, follow these steps:

1. Check Your Current SSL Certificate: Use the openssl command as mentioned earlier to verify the signature algorithm of your existing SSL certificate.
2. Obtain a New SSL Certificate: Contact your Certificate Authority (CA) to request a new SSL certificate that uses a strong signature algorithm. Ensure that the CA supports SHA-256 or SHA-384. Popular CAs include Let's Encrypt, DigiCert, and Comodo.
3. Update Your Server Configuration: Once you have the new certificate, update your server configuration to use the new certificate files. Depending on your server type, the process may vary:

• For Apache: Update your httpd.conf or ssl.conf files:

SSLCertificateFile /path/to/your_domain.crt
SSLCertificateKeyFile /path/to/your_private.key
SSLCertificateChainFile /path/to/chain_file.crt

• For Nginx: Update your server block configuration:

ssl_certificate /path/to/your_domain.crt;
ssl_certificate_key /path/to/your_private.key;

1. Test Your Configuration: After updating your server configuration, restart your web server and test the SSL certificate using the openssl command again to ensure the weak signature algorithm error is resolved.
2. Monitor for Future Issues: Regularly check your SSL certificate and server configurations to ensure compliance with the latest security standards, and consider implementing automated monitoring tools to alert you of any issues.

By following these steps, you can effectively resolve the ERR_CERT_WEAK_SIGNATURE_ALGORITHM error and enhance the security of your web infrastructure.