I am getting hundreds of hits on my server over time that generate an error like the one below. I removed my username from the error. These files that are showing up in my error log, don't exist on my server. Is someone hitting my server, and if so, how?

[Thu Sep 06 17:53:41.904632 2018] [authz_core:error] [pid 19875] [client 39.108.239.20:32341] AH01630: client denied by server configuration: /home/username/html/ak48.php