Product
Pricing
arrow
Get Proxies
arrow
Use Cases
arrow
Locations
arrow
Help Center
arrow
Program
arrow
pyproxy
Email
pyproxy
Enterprise Service
menu
pyproxy
Email
pyproxy
Enterprise Service
Submit
pyproxy Basic information
pyproxy Waiting for a reply
Your form has been submitted. We'll contact you in 24 hours.
Close
Home/ Blog/ What should I do if I encounter “Certificate Error” when switching proxies with FoxyProxy in Firefox?

What should I do if I encounter “Certificate Error” when switching proxies with FoxyProxy in Firefox?

PYPROXY PYPROXY · Jun 19, 2025

When using Firefox with FoxyProxy to switch between different proxies, you might encounter a common issue known as a "certificate error." This happens because the SSL/TLS certificate verification process fails while the proxy server is being switched. Such errors can disrupt your browsing experience and make secure connections to websites impossible. This article will discuss the causes of the error, as well as provide detailed solutions to fix it, helping you to get back to browsing securely without any issues.

Understanding the Cause of the "Certificate Error" in Firefox with FoxyProxy

Before we dive into solutions, it’s important to first understand what causes the "certificate error" when switching proxies with FoxyProxy in Firefox. SSL/TLS certificates are used to ensure that a connection between a browser and a website is encrypted and secure. When you connect through a proxy server, the server acts as an intermediary between your browser and the websites you visit. If the proxy server doesn’t properly handle SSL certificates, Firefox will display a certificate error.

Some common reasons why you may encounter this issue include:

1. Invalid SSL/TLS Certificates: The proxy server might be using outdated or improperly configured certificates.

2. Man-in-the-Middle Attack (MitM): If a proxy intercepts SSL traffic without the proper certificates, it can trigger security warnings.

3. Firefox’s Certificate Revocation Check: Firefox may fail to trust the proxy server’s certificate, especially if it’s not issued by a trusted certificate authority.

4. Proxy Configuration Errors: Incorrect settings in FoxyProxy, such as using a proxy that does not support secure connections, can lead to errors when switching proxies.

Step-by-Step Solutions to Fix "Certificate Error" in Firefox with FoxyProxy

If you’re experiencing a certificate error when switching proxies using FoxyProxy, here are some solutions that can help resolve the issue.

1. Check Proxy Server SSL/TLS Configuration

The first thing you should do is verify that the proxy server you’re using is correctly configured to handle SSL/TLS traffic. Ensure that the server has a valid, up-to-date SSL certificate from a trusted certificate authority (CA). If the certificate is self-signed or expired, the browser will flag it as an error.

- How to check: You can check the certificate details by clicking on the padlock icon in the browser’s address bar when visiting any secure website. Review the certificate information to see if it’s valid or expired.

2. Disable SSL Certificate Verification in FoxyProxy (Temporary Fix)

If the SSL certificate is the cause of the error and you trust the proxy server, you can temporarily disable SSL certificate verification in Firefox to bypass the error. However, this method comes with security risks, as it disables encryption checks.

- Steps to disable SSL verification:

1. Open Firefox and type `about:config` in the address bar.

2. Accept the warning message that appears.

3. Search for `security.ssl.enable_ocsp_stapling` and set it to `false`.

4. Restart Firefox to apply the changes.

This will allow you to use the proxy server even if its SSL certificate is invalid, but it is not recommended for regular use as it weakens your security.

3. Install the Proxy Server’s SSL Certificate in Firefox

If the proxy server uses a self-signed certificate or a certificate that Firefox doesn’t trust, you can manually install the certificate in Firefox’s certificate store. This will allow Firefox to trust the proxy server and establish secure connections.

- Steps to install a certificate:

1. Obtain the SSL certificate from the proxy server (usually available in PEM or DER format).

2. Open Firefox and go to `Options` > `Privacy & Security`.

3. Scroll down to the "Certificates" section and click on `View Certificates`.

4. Click on the `Import` button and select the certificate file you obtained.

5. Follow the prompts to install the certificate as a trusted authority.

Once this is done, Firefox will trust the proxy’s certificate, and you should no longer encounter the certificate error when switching proxies.

4. Clear Firefox’s SSL Cache

Sometimes, cached SSL information can cause conflicts, especially if you’ve previously connected to a site via a different proxy or without one. Clearing the SSL cache in Firefox can resolve these issues.

- Steps to clear SSL cache:

1. Open Firefox and go to `Options` > `Privacy & Security`.

2. Under the "Cookies and Site Data" section, click on `Clear Data`.

3. Ensure the box for "Cached Web Content" is checked, and then click `Clear`.

After clearing the cache, restart Firefox and try connecting via the proxy again to see if the error is resolved.

5. Use a Different Proxy or Proxy Service

If the proxy server you are using is continuously causing certificate errors, it might be a good idea to switch to a different proxy or use a different proxy service. Some proxies have better SSL/TLS handling and are less likely to trigger security warnings in Firefox.

Look for a proxy service that:

- Has updated and valid SSL certificates.

- Is known to support secure and encrypted connections.

- Is compatible with FoxyProxy.

6. Update Firefox and FoxyProxy

Ensure that you’re using the latest versions of both Firefox and the FoxyProxy extension. Software updates often include important security fixes that can address issues with proxy handling and certificate validation.

- How to update Firefox:

1. Click the menu button in the top right corner of Firefox.

2. Select `Help` > `About Firefox`.

3. Firefox will automatically check for updates and install any available updates.

- How to update FoxyProxy:

1. Open the `Add-ons` menu in Firefox (Ctrl+Shift+A).

2. Go to the `Extensions` section and click `Update` next to FoxyProxy if an update is available.

7. Use a VPN as an Alternative

If you continue to face issues with FoxyProxy and certificates, you might consider switching to a VPN (Virtual Private Network) instead. A VPN routes all of your internet traffic through a secure server, eliminating the need for proxies and handling certificate issues in a much more seamless manner.

Encountering a "certificate error" when switching proxies in Firefox using FoxyProxy can be frustrating, but there are multiple solutions available to fix the issue. Whether it’s adjusting your proxy settings, installing the proxy’s SSL certificate, or updating your software, these solutions will help you restore a secure browsing experience. Always ensure that your proxy server is correctly configured, and take necessary precautions when disabling SSL checks or bypassing security features.

Related Posts

Clicky