Unexplained "Unable to create lock file" error log

Every once in a while in my /var/log/asterisk/messages logfile I get a message like:

Sep 5 16:08:20 ERROR[10983] app.c: Unable to create lock file ‘/var/spool/asterisk/voicemail/default/0/Old’: No such file or directory

… followed shortly thereafter by …

Sep 5 16:08:20 ERROR[10983] app.c: Could not unlock path ‘/var/spool/asterisk/voicemail/default/0/Old’: No such file or directory

The directory /var/spool/asterisk/voicemail/default/0 exists and is writeable by the Asterisk process, so I don’t quite understand what is going on here.

It doesn’t seem to be hurting anything but I’m just wondering if I have a misconfiguration somewhere that will come back to bite me later.

for some reason, i have an inkling that a VM box of zero had an issue - in other words, you can’t set up that particular box.

don’t remember where i saw that, but if you don’t absolutely need to use 0 for your VM box, you MIGHT try changing that…

This looks like the mysterious voicemail bug the devs have seen that rarely occur but they were unable to work on it as the issue just disappeared…