On certbot #6971 there is some doubt about whether this will happen.
I’d rather not spend time setting up a workaround to continue using the DST root if it turns out not to be necessary, but I’d also prefer not to be rushing to do that at the last minute.
The planned date is now less than five weeks away. If the transition is still planned I would have expected another blog post on the matter by now. So I’m wondering whether the plan has been changed.
Thanks for the message. We’re still coming up with the exact plan but it does seem likely we’ll push the date farther back. We’ll give an update within the week.
It is very nice from Let’s Encrypt sacrificing a small portion of its credibility to weak up end users of old, unsupported devices. Users of those devices after 29th of September 2020 but before 30th of September 2021 will see the situation (of course, overly simplified) way: “Oh, the websites with letsencrypt certificate do not work any more, but with certificates of every other CA all is fine.”