I use Transmission, a popular BitTorrent client developed for OS X and Unix platforms. I also own a Synology DS415+; whilst it’s possible to run Transmission directly on a Synology NAS, I run Transmission on my iMac and set the NAS as the destination folder for my downloads.
The other day, I began to encounter a problem. Whenever I added a new torrent, Transmission would stop downloading at about 1%, with the error Permission Denied (/Synology/Downloads). This was, naturally, quite irritating, so I set out to find out what was happening.
This error is caused by a bug in Yosemite. If you go to the terminal and type
ls /Volumes
you’ll see a list of the names of the volumes connected to your iMac. In my case, something was immediately a little weird; Synology appeared in the list as it should have done, but Synology-1 was also listed. Ejecting the network drive meant that Synology-1 disappeared, but Synology was still listed.
So, the next Terminal command I typed (based on this Ask Different post) was
sudo rmdir /Volumes/Synology
before remounting the Synology from the Finder. This fixed the problem with Transmission and my torrenting can continue in peace. Hooray!