This error occurs when a file or directory cannot be found. Note, this can happen when creating a file if one of the parent directories doesn't exist, eg:
touch /etc/doesnotexist/foo
will complain with "No such file or directory" since /etc/doesnotexist does not exist.
This error can be returned by many system calls that work with files.
29 pages link to ENOENT:
lib/main.php:944: Notice: PageInfo: Cannot find action page
lib/main.php:839: Notice: PageInfo: Unknown action
lib/plugin/WlugLicense.php:99: Warning: Invalid argument supplied for foreach()