What is Legacy Browser Support?
Legacy Browser Support enables visitors with older browsers and operating systems (together, “user agents”) to continue using HTTPS to connect to your site. Modern browsers that support elliptic curve cryptography (ECC) and SHA-256 signatures will be presented with these certificates, while older browsers (e.g., IE on Windows XP) will be served with older RSA SHA-1 certificates.
What if I don’t care about older browsers?
If your site only needs to be compatible with modern browsers, you can disable this feature. When disabled, we will never serve CloudFlare-issued SHA-1 signed certificates to your visitors, and we will only serve SHA-1 custom certificates if you haven’t uploaded a SHA-2 certificate covering the same hostnames. Be aware that older user agents will no longer be able to connect to your site (and will most likely fail silently rather than indicate an error to the user). Additionally, by disabling SHA-1 support, you now require that browsers use Server Name Indication (SNI).
How can I disable SHA-1 support?
First, if you use custom certificates, make sure you have uploaded a SHA-2 certificate covering the hosts with which you use HTTPS. Then, click the “Disable SHA-1 Support” button and verify that it reads the opposite (i.e., “Enable SHA-1 Support”). You should also now see a warning in the Certificates section, directly about this panel, indicating that SHA-1 certificates are disabled.