Fix Content was blocked because it was not signed by a valid security certificate repair

I have been going through some user reports online and found out that several people encounter the “content was blocked because a valid security certificate did not sign it” error.

This problem is usually encountered when trying to open one or several different pages with Internet Explorer and Microsoft Edge.

But the question is, what brings about this error, and can it be solved?

What causes the ‘content was blocked because a valid security certificate’ error did not sign it?

From my findings, this problem occurs because there was a change in how Internet Explorer treats web pages with an expired (or invalid) security certificate.

For example, in Internet Explorer 8 and the lower versions, a user had an option to continue browsing when they run into a website with an invalid security certificate.

However, when Internet Explorer 11 was introduced, that option was removed ever since. Today users do not have the option to display insecure content via the blue bar on the top of the browser screen.

Content was blocked

Microsoft decided this change to patch up a potential vulnerability among Windows computers.

That said, let me take you through the various scenarios that are known to trigger this particular error message:
  • Internet Explorer is set up to check for server certificate revocation: Internet Explorer has been configured to check for server certificate revocation by default. If you want to get rid of this error if these settings have not been changed, you will have to disable this feature from the advanced menu. The instructions to do this have been described in solution 3.
  • The website with the expired certificate is not added to the list of Trusted Sites – If you are visiting a website that has an expired certificate and it is not added to the trusted sites list then definitely you will run into this error. However, you only need to add that site to the list if you trust the website’s identity with an invalid certificate. Doing this will help you to resolve the issue by adding the website URL to your Trusted List. All the steps to doing this have been discussed in the first solution.
  • Trust issue between Internet Explorer and Symantec Endpoint Protection Manager (SEPM) – Some users have also reported facing this problem after trying to access the SEPM web console from Internet Explorer 11.

After investigating this particular issue, we decided to come up with the following solutions which have worked just fine to repair the “content was blocked because a valid security certificate did not sign it.”

Solution 1: Add the website to your Trusted sites

As I have said earlier, most users encounter the “content was blocked because a valid security certificate did not sign it” error. This happens because they are trying to visit a website whose certificate used to provide identification of the web server contains an error.

If you try to navigate to that site, Internet Explorer will prevent you from landing on the webpage that has an improper certificate.

This is usually helpful; it prevents scenarios where your connection is intercepted, or the webserver you’re trying to reach is misrepresenting your identity.

If you trust the web site’s identity and you know that your connection isn’t compromised, you can use this solution to bypass the Internet Explorer policy.

Below are the steps to help you add the website’s URL to your list of Trusted Sites. 

  1. Open Internet Explorer
  2. Once it is open, click on the Tools button (action menu)
  3. Now select Internet Options.
  4. While you are inside the Internet Options window, go ahead and click on to the Security tab.
  5. Afterward, click on Trusted sites in order to select it and then click the Sites button.
Content was blocked -trusted sites
  1. Now switch back to the website is bringing this error and then copy the website URL.
  2. After copying the URL, switch back to the settings screen, and in the Trusted sites window, simply paste the website URL in the Add this website to the zone box.
  3. After that, disable the box associated with Require server verification (https:) for all sites in this zone and click Add.
Content was blocked -add site
  1. Once you are through with adding the website to your trusted list, close the Internet Options window, and restart your PC.
  2. When the next startup is complete, restart your computer and see if the issue has been resolved.

If you are still encountering the “content was blocked because it was not signed by a valid security certificate” error, please proceed down to the next solution.

Solution 2: Prevent IE from checking for certificate revocation

If you’re still running into this error and add the web page to the list of trusted sites, this method should resolve the issue.

It is one of the quick solutions that have worked out for many users. All you need to do is access the advanced Internet Options for Internet Explorer then prevent the browser from checking for certificate revocation.

Even though this is an easy fix that can help you solve your worries, let me warn you that leaving this option disabled can expose your PC to certain security risks.

Therefore, to ensure that you don’t expose your computer and data to security risks, I advise you to reverse engineer the steps below and revert to the default behavior as soon as you’re done with the website showing the error message.

Here’s what you need to do:

  1. Startup Internet Explorer.
  2. Go to the Tools menu (top-right corner) and click on Internet Options.
  3. When you are on the Internet Options screen, go ahead and click on the Advanced tab.
  4. Under the Settings menu, scroll down to Security and then uncheck the box associated with Check for server certificate revocation. 
  5. Click on the Apply button in order to save the changes to your Security settings.
  6. Close all the running programs and then restart your computer. This will allow the changes to take effect on the next system boot up.

Once your PC restarts, try to visit the same website that was initially showing you the “content was blocked because it was not signed by a valid security certificate” error and see if the issue has been resolved.


If the above steps get you through the problem, please don’t forget to return to the Internet Options window and enable Check for server certificate revocation again to prevent your machine from being at risk.

However, if you’re still encountering the same error message, move down to the next fix below.

Solution 3: Reset the security settings of IE

Several Windows users have reported that they were able to resolve the issue after resetting the Internet Explorer settings.

Please note that this fix may not work for you if you have previously altered the security settings. Also, if you have add-ons or extensions that are capable of modifying default behaviors, this method will not work for you either.

If you never tweaked anything in the browser, proceed with the following guide on resetting IE’s security settings.

  1. Open up the Internet Explorer.
  2. Click on to the action button (tools menu) in the top-right corner of the screen.
  3. Click on Internet Options from the newly opened options menu.
  4. Once the Internet Options screen opens, go to the Advanced tab and then click the Reset button. This should be under Reset Internet Explorer settings.
  5. Next, check the box associated with Delete personal settings in the next prompt.
  6. Now go ahead and click on the Reset button.
Content was blocked -reset settings
  1. Wait for a moment until the reset process is finished and then click on Close once the procedure is finished.
  2. Reboot your PC and check to see if the issue is resolved at the next startup.

If you followed the above procedure correctly, and are still getting the same error message, move it down to the next solution below.

Solution 4: Resolving the Symantec Endpoint Protection Manager with IE conflict (if applicable)

If you bumped into the content was blocked because it was not signed by a valid security certificate” error while accessing the web console of Symantec Endpoint Protection Manager (SEPM), this fix can help.

See, you are probably facing this problem because the browser that you are trying to use does not trust the Symantec Endpoint Protection Manager web page.

If this is the case with the current situation, you will need to obtain a trusted Certificate Authority (CA).

There are several ways you can use to acquire a trusted certificate authority. For this post, we are going to use the easiest way to do this for our none-tech savvy fellows.  

To do this, click on this link official Symantec documentation or right-click on it and then select open in a new tab option.

Alternatively, you can also get the error fixed by installing the manager’s self-signed certificate. To do this, simply follow the steps specific to Internet Explorer from this link (here).

Wrapping Up

I believe that the above workarounds have been of help and that you have now fixed the content was blocked because it was not signed by a valid security certificate” error.

If you are still experiencing the same issue, feel free to let us in the comment section below. Please do mention the type of browser you are using, and we will get back to you soonest.

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This entry was posted in Windows 10 on by .

About James Abuti

James Abuti is a Windows Technical expert and being a passionate Windows Blogger, he loves to troubleshoot system issues and help others. If you wish to contact him directly, you can do so at He is also the founder of and

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