Mozilla PKIX ERROR MITM DETECTED is a common error that many Firefox users have encountered while browsing the internet. This error is caused by a Man-in-the-Middle (MITM) attack, where a third party intercepts the communication between the browser and the website, potentially stealing sensitive information. In this article, we will dive into the root cause of this error, its implications and discuss ways to resolve it. So if you have ever come across this error and are looking for a solution, keep reading to find out more about All About MOZILLA PKIX ERROR MITM DETECTED Error on Firefox.


Are you seeing the “MOZILLA_PKIX_ERROR_MITM_DETECTED” error on your Firefox browser? This error is a security warning that indicates that the connection to the website you are trying to access is being intercepted by a man-in-the-middle (MITM) attack. This means that someone can potentially see and tamper with the data being transmitted between your browser and the website.

While this error may seem alarming, there are several steps you can take to fix the “MOZILLA_PKIX_ERROR_MITM_DETECTED” error on your Firefox browser.

1. Check Your Internet Connection

The first step is to make sure that your internet connection is stable and working properly. If your internet connection is unstable or weak, it can cause interference with the website’s security certificate, leading to the “MOZILLA_PKIX_ERROR_MITM_DETECTED” error. Try restarting your router or connecting to a different network to see if it resolves the issue.

2. Clear Your Browsing Data

Your browser’s cache, cookies, and history can also cause conflicts and lead to security errors. To fix the “MOZILLA_PKIX_ERROR_MITM_DETECTED” error, try clearing your browsing data. To do this, go to the menu in Firefox and select “Options” or “Preferences,” then click on the “Privacy & Security” tab. Under the “Cookies and Site Data” section, click on “Clear Data” and make sure all options are selected. Finally, click “Clear” to remove your browsing data.

3. Update Firefox to the Latest Version

Using an outdated version of Firefox can also cause security errors like the “MOZILLA_PKIX_ERROR_MITM_DETECTED” error. Make sure you have the latest version of Firefox installed on your computer and update it if necessary.

4. Disable Antivirus or Firewall Temporarily

Some antivirus or firewall programs can interfere with your browser’s connection to websites, leading to security errors. To check if this is the case, temporarily disable your antivirus or firewall and try accessing the website again. If the error does not appear, you may need to configure your security software to allow access to the website in question or consider switching to a different security program.

5. Double-check the Website URL

Sometimes, the “MOZILLA_PKIX_ERROR_MITM_DETECTED” error can occur if there is an error in the website’s URL. Make sure you have entered the correct URL in the address bar of your browser and check for any typos or mistakes. If you are accessing a secure website, make sure the URL starts with “https” and not just “http.”

6. Check the Time and Date on Your Device

An incorrect date or time on your device can also cause security errors like the “MOZILLA_PKIX_ERROR_MITM_DETECTED” error. Make sure the date and time are correctly set on your device and try accessing the website again.

7. Contact the Website’s Owner

If none of the above solutions work, the error may be on the website’s end. It is possible that the website’s security certificate has expired or is not configured correctly. In such a case, it is best to contact the website’s owner and inform them of the error.

In conclusion, the “MOZILLA_PKIX_ERROR_MITM_DETECTED” error can be fixed by checking your internet connection, clearing your browsing data, updating Firefox, disabling antivirus or firewall


I am just an engineer who loves technology and loves to encounter technical errors!

Hey Guys, are you familiar with the MOZILLA_PKIX_ERROR_MITM_DETECTED error? This error usually occurs in the Mozilla Firefox browser and can be quite frustrating for users. It usually appears when there is a problem with the connection between the browser and the server, causing a man-in-the-middle attack. Don’t worry, in this article, I will guide you on how to fix the MOZILLA_PKIX_ERROR_MITM_DETECTED error. Before we delve into the solutions, let’s understand what this error means.


The error code MOZILLA_PKIX_ERROR_MITM_DETECTED is an SSL validation error that occurs in the Mozilla Firefox browser. It indicates that the connection between the browser and the server has been compromised, and there is a possibility of a man-in-the-middle (MITM) attack. This type of attack intercepts the communication between two parties and can steal sensitive information like passwords, login credentials, etc.


– Invalid or expired SSL certificate: A secure website should have a valid SSL certificate. If the certificate is invalid or has expired, it can trigger the MOZILLA_PKIX_ERROR_MITM_DETECTED error.
– Outdated browser: An outdated browser can also trigger this error as it may not have the latest security updates to protect against MITM attacks.
– Incorrect date and time settings: The date and time on your device should be accurate, otherwise, it can cause issues with SSL certificates and trigger the MOZILLA_PKIX_ERROR_MITM_DETECTED error.
– Corrupted browser cache: The browser cache stores temporary files and data, and if it gets corrupted, it can cause various errors, including the MOZILLA_PKIX_ERROR_MITM_DETECTED error.
– Firewall or antivirus settings: Sometimes, the security settings on your firewall or antivirus programs can conflict with the browser and cause this error.

Now that we know the possible causes of this error, let’s move on to the solutions.

Solution 1: Check Your SSL Certificate

As mentioned earlier, an invalid or expired SSL certificate can cause the MOZILLA_PKIX_ERROR_MITM_DETECTED error. To check the validity of your SSL certificate, follow these steps:

Step 1: Open Firefox and visit the website that is causing the error.

Step 2: Click on the padlock icon on the left side of the address bar.

Step 3: In the drop-down menu, click on “More Information.”

Step 4: In the Page Info window, click on the “Security” tab.

Step 5: Check the “Connection” section to see if the certificate is valid or expired.

If the certificate is expired or invalid, you will need to contact the website owner and ask them to renew it.

Solution 2: Update Firefox

As mentioned earlier, an outdated browser can also trigger the MOZILLA_PKIX_ERROR_MITM_DETECTED error. To fix this, you need to update your Firefox browser to the latest version. Follow these steps to update Firefox:

Step 1: Open Firefox and click on the menu button (three horizontal lines) on the top-right corner of the window.

Step 2: Click on “Help” in the drop-down menu and then click on “About Firefox.”

Step 3: In the About Mozilla


In conclusion, the MOZILLA PKIX ERROR MITM DETECTED error on Firefox is a security feature designed to protect users from potential man-in-the-middle attacks. It may occur due to various reasons, including invalid security certificates or malicious network connections. Therefore, it is crucial for users to be vigilant and cautious while browsing the internet. By regularly updating their browsers and security settings, users can prevent this error from appearing. Additionally, staying informed about potential online threats and using a reputable antivirus program can also help in mitigating this error. Overall, the MOZILLA PKIX ERROR MITM DETECTED error serves as a reminder for users to prioritize their online security to have a safe and secure browsing experience.

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