EoL for TLS-SNI-01 Validation Support

“February 13, 2019: End-of-Life for All TLS-SNI-01 Validation Support”(Let’s Encrypt Community Support),

Today we are announcing that we will end all support for the TLS-SNI-01 validation method on February 13, 2019.
(snip)
If you’re still using TLS-SNI-01, please switch to one of the other validation methods as soon as possible.