Step -1
If you are using Burp Suite Professional v1.6beta and if you are not able to capture https traffic that means you are using java version 8 or latest.
In order to solve this issue you need to degrade to java below version OR uninstall the current java which you have installed and install Java 7 Installation setup .
Step-2
Download the burp certificate as follow
==>
1. Start burp
2. Configure firefox for loopback proxy (127.0.0.1:8080)
3. type http://burp in firefox and enter ( make sure your burp's intercept should be on )
4. Click on CA certificate, and download it.
5. In firefox Goto Options > Advanced > Certificates > View Certificates > In Authorities Tab > Import the downloaded certificate .
6. Restart the browser
==> Also refer Installing burp's Burp CA Certificate Article.
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