Since September 30, 2021, the official Let's Encrypt organization announced a change that would affect how older browsers and devices trust Let’s Encrypt certificates. If you run a typical website, you will not notice the difference: the vast majority of your visitors will still accept your Let’s Encrypt certificate.
Most websites accept all root certificates present on modern devices and browsers. However, if the device is old and has not received support or updates for years, and therefore lacks compatibility with recent versions, the root certificate may become a problem.
To securely access a website, it is necessary not only for the site to use a protocol such as HTTPS, but also for the device and browser used to have a compatible root certificate that verifies that the connections are secure.
In summary, if you use an old device to browse the internet, websites that have a Let's Encrypt certificate installed may deny the connection because the device cannot verify the certificate.
List of devices and systems that are no longer supported by Let's Encrypt:
Windows XP with Service Pack 3macOS with versions earlier than 10.12.1 (from 2016)iOS with versions earlier than iOS 10 (iPhone 5 is the oldest model that can be updated to iOS 10)Android with versions higher than 2.3.6 and lower than 7.1.1Mozilla Firefox versions older than 2.0Ubuntu versions earlier than 16.04Debian versions earlier than 8Java 8 versions earlier than 8u141Java 7 versions earlier than 3.26Amazon FireOSKindle versions earlier than 3.4.1Cyanogen versions earlier than 10PlayStation consoles with firmware earlier than 5.00BlackBerry versions earlier than 10.3.3
IMPORTANT: We would like to highlight that the free certificate offered by cdmon is Let's Encrypt, therefore these changes also affect hostings where it is installed. Visitors using any of these older devices/systems may be blocked from accessing the site by the certificate itself.