TLS Observatory hangs whenever TLS 1.3 is enabled (including the recommended "Modern" config)

[weinzierl]

For all sites that have TLS 1.3 enabled the TLS Observatory seems to hang indefinitely. This concerns sites with both TLS 1.2 and TLS 1.3 enabled as well as sites that run the Mozilla recommended "Modern" configuration as described here.

Test Cases

Site with Intermediate Configuration

https://weinzierlweb.com

Site with Intermediate Configuration and TLS 1.3 added

https://testing.weinzierlweb.com

Same config as in first example but with
ssl_protocols TLSv1.2 TLSv1.3;
in nginx configuration.

Site with Modern Configuration

https://unstable.weinzierlweb.com

"Modern" configuration as recommended by the moz://a SSL Configuration Generator.

Cloudflare Blog

https://blog.cloudflare.com

Related Issues

• bug: Fail on TLS 1.3-only  #238 is concerned with TLS 1.3 only
• The the page for forum.vodafone.ro is stuck? #226 the site in question seems to have disabled TLS 1.3 now