I’ve come across a fairly famous problem with Filezilla and its inability to properly communicate with some FTP servers. Not that Filezilla did something wrong, it’s just some bad configuration. If you’re stuck with Filezilla not being able to display files from a remote filesystem, this article might just be for you!
Hello people!
Imagine, you’re free all day, you have work that needs to be taken care of and you’re feeling just perfect to attack the work that’s been stacking up over the last few days. I’m talking about configuring some WordPress templates, correcting a few PHP bugs and giving that last job the final cut. Then, just as you’re trying to start your work by connecting to the FTP server, your all-time favorite and free FTP client, Filezilla refuses to grant you access to the files. Trust me folks, this is extremely frustrating – I had to spend all day researching, trying and fiddling around with Filezilla’s setting to come up with a fix for the issue I encountered today.
I’m not saying that my solution is the one and only key to solve this issue, I’m certain it’s not (given that many people have been able to solve the issue with the instructions given on Filezilla’s site, or other resources). Anyway, none of the guides I found helped me in anyway, which is why I had to do my own research, and now I’m giving my experience to you guys – my readers!
Here’s the error I encountered (fourth line from the bottom in the log):
The encountered error message: 226 Transfer done (but failed to open directory). Filezilla was unable to list the remote directory's contents.
What you see is that Filezilla managed to connect to the server, yet was unable to display the remote filesystem’s contents (hence the empty remote-files pane).
Something that was fairly particular to my case was that only one of my server had this kind of issue.
So after some fiddling around in Filezilla’s configuration I noticed that the default remote home directory in the Site Manager (File > Site Manager) was set to root (a simple slash /), which is also the default value for this field. I decided to remove this slash and leave this field empty, which unexpectedly solved the issue for me!
Here’s a screenshot of the Site Manager before I decided to change the default remote directory.
Filezilla's Site Manager before removing the slash (root) from the default remote directory input box.
The reason I believe is that some servers interpret this slash as the root of the filesystem, and not the root of your home directory on the server. Webspace providers usually don’t give their user’s permission to access these areas on the server, which is very reasonable to me.
Since this is fairly easy to try out, I’d suggest trying this fix before playing around with router or firewall configurations!
Feel free to comment this post, I’m more than happy to give further information.
Peace out 
P.S. Here are some of the resources I’ve come across during my research:
Checking whether your ports are properly opened: http://portforward.com/help/portcheck.htm
Filezilla network configuration (recommanded read!!): http://wiki.filezilla-project.org/Network_Configuration
Another article about Active and Passive network configuration:http://www.indiapoly.com/books/fixinf-filezilla-failing-retrieve-directory-listing.html