Situation: Modern versions of Firefox and Chrome prevent access to HTTPS sites using an obsolete encryption cipher. This is done to prevent a logjam attack.
Workaround: As a workaround on Firefox, perform the following steps to regain access to those HTTPS sites, by disabling the obsolete ciphers:
- In a new tab, type or paste about:config in the address bar and press Enter. Accept the warning to be careful.
- In the search box above the list, type or paste dhe and pause while the list is filtered.
- Double-click the security.ssl3.dhe_rsa_aes_128_sha preference to switch it from true to false (disable Firefox from using this cipher)
- Double-click the security.ssl3.dhe_rsa_aes_256_sha preference to switch it from true to false (disable Firefox from using this cipher)
- Reload the site.