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<title>Secure connection failed and Firefox did not connect</title>
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<h1>Secure connection failed and Firefox did not connect</h1>
<p>
This article explains why you may see a
<em>Secure Connection Failed</em> or a
<em>Did Not Connect: Potential Security Issue</em> error page and what
you can do.
</p>
<div id="toc">
<h2>Table of Contents</h2>
<ul>
<li class="toclevel-1">
<a href="#w_secure-connection-cannot-be-established"
><span class="tocnumber">1</span>
<span class="toctext"
>Secure connection cannot be established</span
></a
>
<ul>
<li class="toclevel-2">
<a href="#w_secure-connection-failed"
><span class="tocnumber">1.1</span>
<span class="toctext">Secure Connection Failed</span></a
>
</li>
<li class="toclevel-2">
<a href="#w_did-not-connect-potential-security-issue">
<span class="tocnumber">1.2</span>
<span class="toctext"
>Did Not Connect: Potential Security Issue</span
></a
>
</li>
</ul>
</li>
<li class="toclevel-1">
<a href="#w_website-issues"
><span class="tocnumber">2</span>
<span class="toctext">Website issues</span></a
>
<ul>
<li class="toclevel-2">
<a href="#w_tls-version-unsupported"
><span class="tocnumber">2.1</span>
<span class="toctext">TLS version unsupported</span></a
>
</li>
<li class="toclevel-2">
<a href="#w_hsts-required"
><span class="tocnumber">2.2</span>
<span class="toctext">HSTS required</span></a
>
</li>
</ul>
</li>
<li class="toclevel-1">
<a href="#w_security-software-conflict"
><span class="tocnumber">3</span>
<span class="toctext">Security software conflict</span></a
>
</li>
<li class="toclevel-1">
<a href="#w_incorrect-system-clock"
><span class="tocnumber">4</span>
<span class="toctext">Incorrect system clock</span></a
>
</li>
<li class="toclevel-1">
<a href="#w_other-secure-connection-issues"
><span class="tocnumber">5</span>
<span class="toctext">Other secure connection issues</span></a
>
</li>
</ul>
</div>
<h1 id="w_secure-connection-cannot-be-established">
Secure connection cannot be established
</h1>
<p>
When a website that requires a secure (<strong>https</strong>)
connection tries to secure communication with your computer, Firefox
cross-checks this attempt to make sure that the website certificate and
the connection method are actually secure. If Firefox cannot establish a
secure connection, it will display an error page.
</p>
<h2 id="w_secure-connection-failed">Secure Connection Failed</h2>
<p>
A <em>Secure Connection Failed</em> error page will include a
description of the error, an option to report the error to Mozilla and a
<span class="button">Try Again</span> button. There is no option to add
a security exception to bypass this type of error.
</p>
<p></p>
<p>The error page will also include the following information:</p>
<ul>
<li>
<em
>The page you are trying to view cannot be shown because the
authenticity of the received data could not be verified.</em
>
</li>
<li>
<em
>Please contact the website owners to inform them of this
problem.</em
>
</li>
</ul>
<h2 id="w_did-not-connect-potential-security-issue">
Did Not Connect: Potential Security Issue
</h2>
<p>
Certain secure connection failures will result in a
<em>Did Not Connect: Potential Security Issue</em> error page.
</p>
<p></p>
<p>
The error page will include a description of the potential security
threat, an option to report the error to Mozilla and an
<span class="button">Advanced…</span> button to view the error code and
other technical details. There is no option to add a security exception
to visit the website.
</p>
<h1 id="w_website-issues">Website issues</h1>
<h2 id="w_tls-version-unsupported">TLS version unsupported</h2>
<p>
Some websites try using outdated (no longer secure) Transport Layer
Security(<em>TLS</em>) mechanisms in an attempt to secure your
connection. Firefox protects you by preventing navigation to such sites
if there is a problem in securely establishing a connection. Contact the
owners of the website and ask them to update their TLS version to a
version that is still current and still secure.
</p>
<p>
Starting in Firefox version 74, the minimum TLS version allowed by
default is TLS 1.2. Websites that don't support TLS version 1.2 or
higher will display a <em>Secure Connection Failed</em> error page with
Error code: SSL_ERROR_UNSUPPORTED_VERSION and a message that
<em
>This website might not support the TLS 1.2 protocol, which is the
minimum version supported by Firefox.</em
>
The error page may also include a button,
<span class="button">Enable TLS 1.0 and 1.1</span> that will allow you
to override the minimum TLS requirement; however, Mozilla plans to
remove this option and permanently disable TLS 1.0 and 1.1 in a future
version of Firefox.
</p>
<h2 id="w_hsts-required">HSTS required</h2>
<p>
Other websites may require HTTP Strict Transport Security (HSTS) and
will not allow access with an insecure connection.
</p>
<h1 id="w_security-software-conflict">Security software conflict</h1>
<p>
Many security products use a feature that intercepts secure connections
by default. This can produce connection errors or warnings on secure
websites. If you see secure connection errors on multiple secure
websites, updating your security product or modifying its settings may
resolve the issue.
</p>
<p>
<span class="for" data-for="win8,win10">
Alternatively, you can uninstall third-party security software and use
Windows Defender, the built-in antivirus on Windows 8 and Windows 10.
</span>
</p>
<p></p>
<h1 id="w_incorrect-system-clock">Incorrect system clock</h1>
<p>
Firefox uses certificates on secure websites to ensure that your
information is being sent to the intended recipient and can't be read by
eavesdroppers. An incorrect system date can cause Firefox to detect that
the website's security certificate is expired or invalid. Make sure your
computer is set to the correct date, time and time zone.
</p>
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