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Error Proxy The client failed to negotiate a TLS connection to telemetry.dropbox.com:443: Received fatal alert: unknown_ca

Hazen | Last updated: Apr 02, 2020 04:14PM UTC

I'm getting the follwing errors when attempting to use Burp to analyse web traffic. Any site that uses HSTS gets the following error: 1585841893062 Error Proxy The client failed to negotiate a TLS connection to [url.gtld]:443: Received fatal alert: unknown_ca I have installed the BurpSuite PortswiggerCA into the Trusted Root Authorities on the target host and cannot use Chrome, Firefox, Opera or Edge to browse the test site as a result of this error.

Ben, PortSwigger Agent | Last updated: Apr 02, 2020 05:51PM UTC

Hi Jason, Have you installed the Burp CA Certificate in the browser that you are using alongside Burp (you can find out the installation steps for your browser from the following page - https://portswigger.net/support/installing-burp-suites-ca-certificate-in-your-browser)?

c0d3x27 | Last updated: Sep 02, 2021 03:47PM UTC

Ben, Sometime no answer is better than a stupid answer. The guy just told you that he got the ca certificate installed but is still not working. I have the same problem which is why im here. But i Have this problem not because dumb and i dont know how to used this web app. IT just that stopped working for no reason at all. You guys just need to find out what changed on these browsers update that made the web app stop working. Thats where the real problem is at. ya should start by looking at about:config

Ben, PortSwigger Agent | Last updated: Sep 02, 2021 06:33PM UTC

Hi, This is a fairly old forum thread so it would be useful if you were able to provide us with more details about the specific issue that you are experiencing? - Are you receiving the same unknown_ca error message as the original poster or something different? - Are you experiencing this issue with one site in particular or is it happening to various sites? - If it is a single site (or a handful of sites) are you able to share the URL of the site(s) so that we can take a look?

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