As the digital world continues to grow and evolve, the importance of secure connections between servers and clients cannot be understated. SSL/TLS encryption is a vital component in ensuring data privacy and integrity. However, navigating the complex landscape of web security can be challenging, especially when encountering issues like the “Error: 0A00018E SSL Routines: CA MD Too Weak.” In this blog post, we’ll delve into the details of this error, exploring its causes and offering solutions to maintain a secure web environment.

Understanding the Error: 0A00018E SSL Routines: CA MD Too Weak

The “0A00018E SSL Routines: CA MD Too Weak” error arises when an SSL/TLS connection fails due to the server’s certificate authority (CA) using an insecure message digest algorithm. Message digest algorithms are essential for producing a certificate’s digital signature. When a CA employs a weak algorithm, the SSL/TLS handshake between the server and client cannot be completed, preventing a secure connection.

Causes of the Error

The main reason for this error is the utilization of weak or outdated message digest algorithms, such as MD5 or SHA-1. These algorithms have known vulnerabilities and are no longer deemed secure:


First published in 1992, MD5 has been considered compromised since 2004, when researchers demonstrated various successful attacks against it. As a result, MD5 should not be used in any security-related applications.


Introduced in 1995, SHA-1 is also considered insecure due to identified vulnerabilities. In 2017, researchers carried out the first practical collision attack against SHA-1, proving that it is unsuitable for security purposes.

Identifying the Error

To check if a server’s certificate is using a weak message digest algorithm, you can use several tools, including OpenSSL or online SSL checkers. For example, to verify this with OpenSSL, execute the following command:

openssl s_client -connect -servername | openssl x509 -noout -text

Inspect the output for the “Signature Algorithm” line to determine which algorithm the certificate employs.

Fixing the Error

To resolve the “0A00018E SSL Routines: CA MD Too Weak” error, follow these steps:

Obtain a New SSL/TLS Certificate

Contact your CA and request a new certificate that uses a secure message digest algorithm, such as SHA-256 or higher.

Install the New Certificate

Replace the existing certificate on your server with the new, secure one. Refer to your server’s documentation for the specific installation process.

Verify the Certificate Installation

Utilize OpenSSL or an online SSL checker to ensure that the new certificate is properly installed and configured.

Update Server Software

Keep your server software up to date to avoid potential security vulnerabilities or compatibility issues.

Configure Intermediate Certificates

Make sure intermediate certificates are correctly configured on your server. This step is crucial for maintaining a proper certificate chain.

Preventing Future Issues

To avoid similar errors in the future, consider adopting the following best practices:

Use Strong Message Digest Algorithms

Always choose SHA-256 or higher when obtaining SSL/TLS certificates.

Keep Server Software Up to Date

Regularly update your server software to minimize the risk of security vulnerabilities.

Monitor Certificate Expiration

Employ monitoring tools to track certificate expirations and renew them before they expire.

Implement a Robust Certificate Management Process

Develop a process for managing SSL/TLS certificates, including obtaining, installing, and renewing them. This will help ensure your certificates remain secure and up to date.

Follow Industry Best Practices

Stay informed about the latest developments in web security and encryption, and adopt industry-recommended practices to maintain a secure online presence.


The “Error: 0A00018E SSL Routines: CA MD Too Weak” is a critical issue that occurs due to the use of insecure message digest algorithms in SSL/TLS certificates. To maintain a secure web environment, it is essential to obtain certificates that use strong algorithms, such as SHA-256 or higher. By following the steps outlined in this blog post, you can effectively resolve this error and prevent future issues by adopting best practices in SSL/TLS certificate management. Stay vigilant and proactive in ensuring your online security to provide a safe and secure experience for your users.

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