I setup LetsEncrypt on 2 websites just a couple of months ago. They failed to renew a few days ago.
The first problem seems to be a permissions problem. mkdir failed with an authentication error. I had to change the owner from root to the website owner. Note that the root ownership was setup by the LetsEncrypt script, not me.
This solved the mkdir problem, and one of the websites successfully updated, but another website still is not working. There error from LetsEncrypt is:
urn:acme:error:connection :: The server could not connect to the client to verify the domain :: Fetching https://[mydomain].com.well-known/acme-challenge/7vJOv440Bx89-T-W7vTEJ60_WgZx2T_W9w79A_lAaXM: Error getting validation data
Note that there is a missing forward-slash between the .com in the domain, and the .well-known directory. I have no redirects, nor anything special in the server setup.
Any help would be appreciated.