Guide to SSL Errors: What do they mean and how to fix them

SSL error messages are a common source of frustration for website users, SSL errors are not just technical nuisances, they’re critical warnings that affect website credibility and user trust. Whether you’re a site owner or a visitor, knowing what an SSL error means and how to resolve it is essential for staying secure online.

In this guide, we will dive into each SSL error meaning, examine the vital role of SSL certificates in securing websites, discuss common SSL connection errors with practical solutions and how we can fix SSL errors in both servers and clients.

What is an SSL Certificate?

An SSL (Secure Sockets Layer) certificate is a digital credential that establishes a secure, encrypted connection between a user's browser and a website’s server. It ensures that sensitive data, such as passwords, credit card details, and personal information, is transmitted securely, protecting it from interception.

What is an SSL Error?

Most commonly youd see messages like "An SSL error has occured" when a client (like web browser) cannot establish a secure connection with the server (like website). This could be due to issues with the SSL certificate, the server configuration, or the client configuraration itself.

The result is a broken connection that may expose sensitive information or stop entirely to prevent this.

Why SSL Certificates Are Essential for Secure Connections

SSL certificates are crucial for maintaining online security. They protect sensitive information and ensure trust between websites and their users. Without them, websites become vulnerable to cyberattacks, and users are less likely to interact with untrusted sites.

SSL certificates enhance data security by encrypting sensitive information like passwords and payment details during transmission. They also build user trust by displaying the padlock icon in browsers, signaling a secure connection. Additionally, they offer an SEO advantage, as Google favors HTTPS-secured websites in search rankings.

Consequences of Not Having SSL Certificates

Without an SSL certificate, websites risk losing user trust, exposing sensitive data, and dropping in search engine rankings. Here’s how these issues affect your site:

• Loss of Trust and Traffic: "Not Secure" warnings drive visitors away, reducing engagement.
• Security Risks: Unsecured websites are prone to phishing attacks, exposing sensitive user information.
• Lower SEO Rankings: Search engines deprioritize non-HTTPS sites, leading to reduced visibility and traffic.

What Causes an SSL Connection Error?

SSL connect error can result from a variety of issues, including expired certificates, misconfigurations, or outdated protocols. Below are common SSL error scenarios, their causes, impacts, and associated error codes:

1. Expired SSL Certificate

• Cause: The SSL certificate's notAfter date has passed, meaning it is no longer valid.
• Impact: Browsers warn users that the site is insecure, reducing trust and driving visitors away.
• Common Codes/Details:
  • NET::ERR_CERT_DATE_INVALID (Chrome)
  • SEC_ERROR_EXPIRED_CERTIFICATE (Firefox)
  • SSL_ERROR_CERT_HAS_EXPIRED (OpenSSL)
  • CURLE_PEER_FAILED_VERIFICATION (curl) with additional details about date invalidation

2. Invalid SSL Certificate

• Cause: The certificate is invalid due to being self-signed, revoked, or issued by an untrusted Certificate Authority (CA).
• Impact: Users see warnings like "Your connection is not private," which erodes trust and deters access.
• Common Codes/Details:
  • NET::ERR_CERT_AUTHORITY_INVALID (Chrome)
  • SEC_ERROR_UNKNOWN_ISSUER (Firefox)
  • SSL_ERROR_CERTIFICATE_VERIFY_FAILED (OpenSSL)
  • CURLE_PEER_FAILED_VERIFICATION (curl)

3. Name Mismatch Error

• Cause: The hostname in the URL does not match the Common Name (CN) or Subject Alternative Name (SAN) specified in the SSL certificate.
• Impact: Browsers display a mismatch warning, creating doubt about the site’s legitimacy.
• Common Codes/Details:
  • NET::ERR_CERT_COMMON_NAME_INVALID (Chrome)
  • SEC_ERROR_CERT_DOMAIN_MISMATCH (Firefox)
  • SSL_ERROR_BAD_CERT_DOMAIN (OpenSSL)
  • CURLE_PEER_FAILED_VERIFICATION (curl)

4. Wrong Host Configuration

• Cause: The server is misconfigured, sending the wrong certificate for the requested domain.
• Impact: Users encounter errors, potentially losing trust and leaving the site.
• Common Codes/Details:
  • NET::ERR_SSL_PROTOCOL_ERROR (Chrome)
  • SSL_ERROR_SYSCALL or SSL_ERROR_ZERO_RETURN (OpenSSL)
  • SSL_ERROR_INTERNAL_ERROR_ALERT (Firefox)
  • May manifest as ERR_SSL_VERSION_OR_CIPHER_MISMATCH (Chrome)

5. Revoked SSL Certificate

• Cause: The SSL certificate has been revoked by the issuing Certificate Authority (CA), often due to compromise or policy violation.
• Impact: Browsers block access to the site, leading to loss of traffic and credibility.
• Common Codes/Details:
  • NET::ERR_CERT_REVOKED (Chrome)
  • SEC_ERROR_REVOKED_CERTIFICATE (Firefox)
  • May trigger CURLE_PEER_FAILED_VERIFICATION (curl)

6. Untrusted Root Certificate

• Cause: The certificate chain cannot be verified back to a trusted root Certificate Authority.
• Impact: Users are warned about the untrusted site, causing distrust and abandonment.
• Common Codes/Details:
  • NET::ERR_CERT_AUTHORITY_INVALID (Chrome)
  • SEC_ERROR_UNKNOWN_ISSUER (Firefox)
  • SSL_ERROR_SELF_SIGNED_CERT_IN_CHAIN (OpenSSL)
  • CURLE_PEER_FAILED_VERIFICATION (curl)

7. SSL/TLS Version or Cipher Mismatch

• Cause: The client and server fail to negotiate a compatible SSL/TLS protocol version or cipher suite due to outdated or misconfigured settings.
• Impact: The connection fails, preventing users from accessing the site.
• Common Codes/Details:
  • ERR_SSL_VERSION_OR_CIPHER_MISMATCH (Chrome)
  • SSL_ERROR_UNSUPPORTED_VERSION or SSL_ERROR_UNSUPPORTED_CIPHER_SUITE (OpenSSL)
  • CURLE_SSL_CONNECT_ERROR (curl)

8. Certificate Signature Algorithm Not Supported

• Cause: The SSL certificate uses an insecure or outdated signature algorithm, such as SHA-1, which modern browsers and tools no longer support.
• Impact: Users encounter warnings about weak encryption, reducing trust and engagement.
• Common Codes/Details:
  • NET::ERR_CERT_WEAK_SIGNATURE_ALGORITHM (Chrome)
  • SEC_ERROR_CERT_SIGNATURE_ALGORITHM_DISABLED (Firefox)

9. Certificate Chain Issues

• Cause: Problems with intermediate certificates, such as a missing certificate in the chain or a broken trust path.
• Impact: The certificate cannot be validated, leading to warnings about an untrusted site.
• Common Codes/Details:
  • NET::ERR_CERT_AUTHORITY_INVALID (Chrome)
  • SEC_ERROR_UNKNOWN_ISSUER (Firefox)
  • X509_V_ERR_UNABLE_TO_GET_ISSUER_CERT_LOCALLY (OpenSSL)

10. Protocol Errors

• Cause: Errors in the SSL/TLS handshake, such as malformed packets, unsupported extensions, or incompatibility between the client and server.
• Impact: The connection fails, and users are unable to access the site securely.
• Common Codes/Details:
  • NET::ERR_SSL_PROTOCOL_ERROR (Chrome)
  • SSL_ERROR_HANDSHAKE_FAILURE_ALERT (Firefox)
  • SSL_ERROR_SYSCALL (OpenSSL)

Summary Table of Errors, Causes, and Impacts

Error Scenario	Cause	Impact	Common Codes/Details
Expired SSL Certificate	Certificate’s validity expired	Users see warnings; loss of trust	NET::ERR_CERT_DATE_INVALID, SSL_ERROR_CERT_HAS_EXPIRED
Invalid SSL Certificate	Self-signed or issued by untrusted CA	“Connection not private” warnings; users deterred	NET::ERR_CERT_AUTHORITY_INVALID, SSL_ERROR_CERTIFICATE_VERIFY_FAILED
Name Mismatch Error	Hostname mismatch with certificate	Browser mismatch warnings; users lose confidence	NET::ERR_CERT_COMMON_NAME_INVALID, SSL_ERROR_BAD_CERT_DOMAIN
Wrong Host Configuration	Misconfigured server	Connection failures; trust diminished	NET::ERR_SSL_PROTOCOL_ERROR, SSL_ERROR_SYSCALL
Revoked SSL Certificate	Certificate revoked by issuing CA	Users blocked from accessing site	NET::ERR_CERT_REVOKED, SEC_ERROR_REVOKED_CERTIFICATE
Untrusted Root Certificate	Chain doesn’t verify to trusted CA	Users see untrusted site warnings; traffic drops	NET::ERR_CERT_AUTHORITY_INVALID, SSL_ERROR_SELF_SIGNED_CERT_IN_CHAIN
SSL/TLS Version Mismatch	Outdated protocols or ciphers	Connection failures; site inaccessible	ERR_SSL_VERSION_OR_CIPHER_MISMATCH, SSL_ERROR_UNSUPPORTED_VERSION
Weak Signature Algorithm	Outdated algorithms like SHA-1	Users warned of insecure site	NET::ERR_CERT_WEAK_SIGNATURE_ALGORITHM, SEC_ERROR_CERT_SIGNATURE_ALGORITHM_DISABLED
Certificate Chain Issues	Missing or broken intermediate certificate chain	Untrusted certificate errors; users lose confidence	NET::ERR_CERT_AUTHORITY_INVALID, X509_V_ERR_UNABLE_TO_GET_ISSUER_CERT_LOCALLY
Protocol Errors	Handshake failure, unsupported extensions	Connection fails; users unable to access site	NET::ERR_SSL_PROTOCOL_ERROR, SSL_ERROR_HANDSHAKE_FAILURE_ALERT

Understanding SSL Errors: The Client Perspective

From the client’s perspective, SSL errors pose challenges for developers working on web scraping, API integrations, or automation tools, disrupting workflows, causing request failures, and potentially introducing security risks.

Common SSL Error Scenarios for Clients

SSL errors can disrupt web scraping, API calls, and automation tasks due to expired certificates or hostname mismatches.

1. Web Scraping and Data Collection Fails

When scraping data from a website, SSL errors like expired or self-signed certificates can prevent tools such as Python's requests library or Node.js scripts from retrieving data. This disrupts workflows and may require additional configuration or SSL bypassing to resume operations.

2. Testing and Development with Self-Signed Certificates

Local development environments often use self-signed SSL certificates, which aren’t trusted by default. This results in browser warnings or failed requests in HTTP clients, adding friction to testing and debugging.

3. Automation Tools Blocked by SSL Warnings

Scheduled tasks using tools like curl, wget, or automation scripts may fail when interacting with endpoints that have SSL issues, such as invalid certificates or hostname mismatches. This disrupts automated workflows and can lead to delays in data processing or API communication.

You can learn more about cURL vs Wget in our dedicated article:

cURL vs Wget: Key Differences Explained

Explain the key differences between these two powerful utilities and help you decide when to choose cURL and when to opt for wget.

4. Access to Third-Party APIs Is Restricted

APIs hosted on servers with outdated certificates or unsupported TLS protocols may block client requests. This is common when dealing with legacy systems or improperly maintained APIs.

Impacts of SSL Errors on Clients

SSL errors can significantly affect clients by interrupting processes, increasing troubleshooting efforts, and posing security risks. Below are key ways these errors impact client workflows and resource access.

• Workflow Disruption: Failed API calls or scraping scripts halt data collection, testing, or automation tasks.
• Increased Debugging Time: Diagnosing and resolving SSL issues can be time-consuming, especially when multiple tools or libraries are involved.
• Security Risks: Bypassing SSL verification, while convenient, can expose clients to potential man-in-the-middle attacks if the source is compromised.
• Resource Accessibility Issues: Important resources or APIs may become temporarily inaccessible due to SSL-related failures.

How to Fix SSL certificate issues

To fix SSL errors effectively, the first step is identifying the root cause. Use tools like SSL Checker to detect issues with certificate validity and server configuration. Additionally, Browser Developer Tools can provide detailed error messages during the SSL handshake process.

Common SSL Errors and Their Solutions:

Error	Solution
Expired SSL Certificate	Reenew the certificate promptly through your Certificate Authority (CA) and reinstall it on your server to restore secure connections.
Invalid SSL Certificate	Purchase an SSL certificate from a trusted CA (e.g., DigiCert or GlobalSign) and install it properly to establish trust.
Name Mismatch Error	Generate a new Certificate Signing Request (CSR) and ensure the reissued certificate includes all domain variations, such as “www” and non-“www.”
Wrong Host Configuration	Update server configurations to ensure the certificate matches the intended domain or subdomain.

Ensuring regular updates and monitoring can help you maintain a secure and trusted website environment, minimizing disruptions and safeguarding user trust.

Ignoring SSL Errors from the Client Perspective

In some cases, such as web scraping or testing, the security risks of ignoring SSL validation are minimal, and bypassing SSL verification can be a practical solution. Most HTTP clients provide an option to disable SSL verification.

Here are some examples of how to disable SSL verification:

Python (Requests Library)

The Python requests library is a popular choice for making HTTP requests. If you encounter SSL errors and need to bypass SSL verification temporarily, you can use the verify=False option. Here’s how:

import requests

response = requests.get('https://httpbin.dev', verify=False)

• Key Option: verify=False disables SSL verification.

JavaScript (Axios)

Axios is a widely-used HTTP client for JavaScript and Node.js. To bypass SSL errors in Node.js, configure the https.Agent with rejectUnauthorized: false. This option prevents certificate validation for HTTPS requests. Here’s an example:

const axios = require("axios");

axios
  .get("https://httpbin.dev", {
    httpsAgent: new (require("https").Agent)({ rejectUnauthorized: false }),
  })
  .then((response) => console.log(response.data))
  .catch((error) => console.error(error));

• Key Option: rejectUnauthorized: false in the https.Agent configuration.

cURL

cURL is a versatile command-line tool for making HTTP requests. When SSL errors block access to a resource, you can use the -k (or --insecure) flag to bypass SSL verification and complete the request. Here’s an example:

curl -k https://httpbin.dev

• Key Option: -k or --insecure bypasses SSL certificate validation.

PHP (cURL)

PHP’s cURL library allows you to make HTTP requests with flexible options. If SSL errors are preventing successful connections, you can use the CURLOPT_SSL_VERIFYPEER option to disable SSL verification temporarily. Here’s how it works:

$ch = curl_init();
curl_setopt($ch, CURLOPT_URL, "https://httpbin.dev");
curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1);
curl_setopt($ch, CURLOPT_SSL_VERIFYPEER, false); // Disable SSL verification
$output = curl_exec($ch);
curl_close($ch);

echo $output;

• Key Option: CURLOPT_SSL_VERIFYPEER set to false.

Ruby (Net::HTTP)

Ruby’s Net::HTTP library is a simple way to handle HTTP requests. If SSL verification errors are an obstacle, you can bypass them by setting VERIFY_NONE in the SSL configuration. Here’s an example:

require 'net/http'
require 'openssl'

uri = URI('https://httpbin.dev')
http = Net::HTTP.new(uri.host, uri.port)
http.use_ssl = true
http.verify_mode = OpenSSL::SSL::VERIFY_NONE # Disable SSL verification

request = Net::HTTP::Get.new(uri)
response = http.request(request)

puts response.body

• Key Option: VERIFY_NONE disables SSL verification.

FAQ

To wrap up this guide, here are answers to some frequently asked questions about SSL error

How do I check if my SSL certificate is working?

Use online tools like SSL Checker or SSL Labs to verify your certificate's validity, configuration, and expiration status.

Do SSL certificates improve SEO?

Yes, search engines like Google prioritize HTTPS-secured websites, which can boost your site’s search engine ranking and visibility.

Why do I see the message: “We could not verify the certificate: reason = wronghost”?

This error means the SSL certificate was issued for a domain different from the one accessed. Check and update the domain name configuration on the server.

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Summary

SSL errors can undermine website security and deter users from engaging with your site. By understanding the causes of errors, such as expired certificates or name mismatches, and implementing solutions like renewing certificates or correcting configurations, you can maintain a secure and trusted website.

By addressing SSL issues promptly and following best practices, you can ensure a seamless and secure browsing experience for your users.