"This Connection is Untrusted" error message appears - What to do
This article describes why the This Connection Is Untrusted error message may appear when trying to visit secure (https) websites in Firefox.
- For troubleshooting secure connection problems with the error message Secure Connection Failed, see the Troubleshoot the "Secure Connection Failed" error message article.
- For troubleshooting other error messages, see Websites don't load - troubleshoot and fix error messages.
Table of Contents
- 1 Certificates and identification
- 2 Get out of there!
- 3 Technical information
- 3.1 Certificate will not be valid until (date)
- 3.2 The certificate expired on (date)
- 3.3 Certificate is only valid for (site name)
- 3.4 The certificate is not trusted because the issuer certificate is unknown
- 3.5 The certificate is not trusted because no issuer chain was provided
- 3.6 The certificate is not trusted because it is self-signed
- 4 Bypassing the warning
Certificates and identification
When you visit a website whose web address starts with https, your communication with the site is encrypted to help ensure your privacy. Before starting the encrypted communication, the website will present Firefox with a "certificate" to identify itself.
The certificate helps Firefox determine whether the site you're visiting is actually the site that it claims to be. If there is a problem with the certificate, you will see the This Connection Is Untrusted alert page.
Seeing the alert does not necessarily mean that the website you're visiting is trying to trick you into believing it is a different website - it means that Firefox isn't able to verify the identity of the website, and that you should proceed carefully.
There are several problems that can cause Firefox to reject a certificate. Some of them are described in detail in the Technical information section below.
Get out of there!
The safest thing to do is to click, or to go to a different website. Unless you know and understand the technical reason why the website presented incorrect identification, and are willing to risk communicating over a connection that could be vulnerable to an eavesdropper, you should not proceed to the website.
If possible, you should contact the owners of the website and inform them of the error.
Click on Technical Details for more information on why the website's identity information is invalid. Some common errors are described below.
Certificate will not be valid until (date)
This error can occur if your computer clock has the wrong date, in which case the date given in the error message will be in the past. To fix the problem, set your system clock to today's date and time (double-click the clock icon on the Windows Taskbar).
The certificate expired on (date)
This error occurs when a website's identity certification has expired.
This error can also occur if your computer clock has the wrong date. To fix the problem, set your system clock to today's date and time (double-click the clock icon on the Windows Taskbar).
Certificate is only valid for (site name)
This error is telling you that the identification sent to you by the site is actually for another site. While anything you send would be safe from eavesdroppers, the recipient may not be who you think it is.
A common situation is when the certificate is actually for a different part of the same site. For example, you may have visited https://example.com, but the certificate is for https://www.example.com. In this case, if you access https://www.example.com directly, you should not receive the warning.
The certificate is not trusted because the issuer certificate is unknown
The file cert8.db in your profile folder may have become corrupted. Delete this file while Firefox is closed.
Open your profile folder:
At the top of the Firefox window, click on the button, go over to the menuOn the menu bar, click on the menuAt the top of the Firefox window, click on the and select menu . The Troubleshooting Information tab will open.
- Under the Application Basics section, click on filesfolder will open. . A window with your profile
- At the top of the Firefox window, click on the button and then select At the top of the Firefox window, click on the menu and then select On the menu bar, click on the menu and select At the top of the Firefox window, click on the menu and select
- Click on the file named cert8.db.
- Press command+Delete.
- Restart Firefox.cert8.db will be recreated when you restart Firefox. This is normal.
The certificate is not trusted because no issuer chain was provided
You may have enabled SSL scanning in your security software such as ESET or BitDefender. Try to disable this option.
The certificate is not trusted because it is self-signed
Self-signed certificates make your data safe from eavesdroppers, but say nothing about who the recipient of the data is. This is common for intranet websites that aren't available publicly.
Bypassing the warning
You should only bypass the warning if you're confident in both the identity of the website and the integrity of your connection - even if you trust the site, someone could be tampering with your connection. Legitimate public sites will not ask you to add connection rule exceptions - an invalid certificate can be an indication of a web page that will defraud you or steal your identity.
- On the warning page, click I Understand the Risks.
- Click . The Add Security Exception dialog will appear.
- Read the text describing the problems with this site.
- Click if you want to trust the site.
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