xfer problems between 2.3.15 and 2.4.17

[Andrew Morgan]

On Tue, 10 Jun 2014, gavin.gray at ed.ac.uk wrote:

> Hi Wes,
>
> It looks like the whole mupdate thing is working perfectly well.
> If I create a folder while connected to my 2.4.17 frontend then the logs show 
> the backend issuing the cmd_set and then a bunch of cmd_find going out 
> including to the frontend in question. Furthermore the new folder really is 
> there in the mailboxes.db on the frontend. So in a way that's reassuring, but 
> then why is the frontend telling email clients that the folder doesn't exist 
> when a request to subscribe to it comes in? We aren't seeing any kick_mupdate 
> getting logged.

I'm pretty sure your problem is that you have the proxyservers variable 
set in imapd.conf on your frontend.  See this message from the archives:

   http://asg.andrew.cmu.edu/archive/message.php?mailbox=archive.info-cyrus&searchterm=Murder%20mailbox%20create%20race%20condition&msg=54193

I ran into this same problem, which was introduced by changes in v2.4.13. 
The imapd.conf manpage says:

   proxyservers: <none>
        A list of users and groups that are allowed to proxy for  other  users,  separated  by
        spaces.  Any user listed in this will be allowed to login for any other user: use with
        caution.  In a standard murder this option should ONLY be set on backends.  DO NOT SET
        on frontends or things won't work properly.

Let us know if removing proxyservers from your frontends fixes the 
problem!

 	Andy