and yes you are allowed to use it. It’s not written or maintained by Let’s Encrypt, you are allowed to use it though.
That plugin doesn’t look as if it’s actively maintained, and there are a number of open issues (if you check the above link).
The error you are seeing is that when a token is placed in your
webroot/.well-known/acme-challenge/token
Then Let’s Encrypt tries to verify that from the internet. going to http://grayles.net/.well-known/acme-challenge/token it gets a 404 error - page no found. Exactly why it get’s a 404 I can’t be certain. If you place a file there yourself, is it reachable from the internet ?
Well that link should at least start guiding you in the right direction, I’ve never used Plesk but have been using apache for years and that seems definitely to be a problem with the ACME challenge not working. You need to check your apache rules depending on version 2.2 or 2.4. 2.4 introduced changes to the way you grant access to locations. So depending on your Apache version I would start there, there is a lot of threads in here that might give you your answer, just search properly especially for “ACME challenge apache rules”
Update: I followed the fixes, now i get a new error (though much shorter then the last one)
Error: Let's Encrypt SSL certificate installation failed: Failed letsencrypt execution: Saving debug log to /opt/psa /var/modules/letsencrypt/logs/letsencrypt.log
Obtaining a new certificate
Performing the following challenges:
http-01 challenge for grayles.net
filemng: Error occurred during /bin/mkdir command.
Cleaning up challenges
Command '['/usr/local/psa/admin/bin/filemng', u'hotpotsoup', 'mkdir', '-p', u'/var/www/vhosts/grayles.net/httpdocs/.well-known/acme-challenge']' returned non-zero exit status 1
It would appear to be having a problem creating the directory .well-known/acme-challenge/ in your webroot (i.e. the folder where the top level index page for your site is). What are the ownership permissions on that folder ? does the .well-known folder exist ? if not can you create it and retest ?
As @serverco mentioned, the best way to test is to manually create the .well-known folder in your site, place a plain text file in there test.txt for instance and see if you can access that from a browser. If you can access it then the ACME challenge should work but if you can not access yoursite.com/.well-known/test.txt then you still have permission issues on apache.
That guide looks OK for permissions. yes. Your error is now not one of permissions though, rather a 404 error is “file not found”
Have you got the correct directory ? if I go to http://grayles.net/ I get the default apache page which says it’s at /var/www/html/index.html … if you edit the index file slightly can you see the change in your browser ? that way you will see if the file is really in /var/www/html/index.html or in /var/www/vhosts/grayles.net/index.net
I’m not sure how you set up your websites, so don’t know. (do you have more than one website on the server ? or just one ? Did you follow a particular method in setting up your apache config ? if so what ?
And I did a reinstallation of apache2, not too long ago. I stopped the service - uninstalled - purged and did a "sudo apt-get install apache2 " on top.
Do you think I should start again? Perhaps i didn’t do the configuration properly?
Yes, I’d suggest starting again. uninstalling, purging and reinstalling apache would have put the default apache config in - which would have overwritten all your plesk config for apache.