Every now and then when previewing Hugo (via hugo serve) as I'm editing it in Emacs I'll get a strange error like:

ERROR 2021/10/18 19:36:03 process: readAndProcessContent: walk:
Readdir: decorate: lstat
/home/user/skeptric/content/user@machine.2139:12345 no such file or directory

Often I can work around it by editing and saving the file I've been editing again, but I'll have to restart the Hugo process. However the underlying cause is lockfiles in Emacs, and the easiest fix is to run the elisp (in 24.3 and above):

(setq create-lockfiles nil)

Explanation

If I got the above error when editing a file called about.md I'd normally be able to find a symlink like .#about.md -> user@machine.2761:12345. This turns out to be emacs system for file locks. The .#<filename> is symlinked to <user>@<host>.<pid>:<time since boot>. Then when another user tries to to open the file in emacs it will then complain about the file being locked. You can turn this off by setting create-lockfiles to nil.

Hugo tries to follow these symlinks and realising they're not going to a real file complains. Unfortunately I can't find any way to disable this behaviour of Hugo, and since I'm not in a multiuser environment it seems the only solution is to turn off Emacs lockfiles.