Infinite loop of "pre-transfer > retry" when trying to upload.

Recently I've been having a problem uploading that I've literally never had in all the years before now.

When I try to upload a file, it goes to "pre-transfer" and sits there for a second, then goes to "retry at" and sits there for a second, then back to pre-transfer and this goes on and on and the file never uploads.

This doesn't happen every time, just a lot of the time. And sometimes after letting this annoying process go on and on for a while, I'll stop it and start it again and it actually uploads on the first try. No idea what the hell that's about.

Here's the most recent example from the log:

[18:38:58] Operation Begin
[18:38:58] Remote file exist check: "file.gif".
[18:38:58] MLST file.gif
[18:39:01] 500 Syntax error, command unrecognized.
[18:39:01] SIZE file.gif
[18:39:01] 550 No such file.
[18:39:01] File exist check failed. File not found or permission denied.
[18:39:01] PASV
[18:39:01] 227 Entering Passive Mode (xx,xx,xx,xxx,xxx,xx)
[18:39:01] Opening data connection to xx.xx.xx.xxx Port: 65369
[18:39:01] STOR file.gif
[18:39:01] 553 Permission denied.
[18:39:01] Transfer failed.
[18:39:01] Operation End

Any ideas? Thanks in advance.

Permission problem:
[18:39:01] STOR file.gif
[18:39:01] 553 Permission denied.

Please contact your web hosting provider.

Did it. The user for that directory was "nobody" so I wasn't able to upload/edit/delete/etc.

Thanks for the help!

Actually, while I was able to fix that specific problem in the previously mentioned post of mine, this problem still continues to occur in other cases.

Here's an example log:

[19:01:47] Operation Begin
[19:01:47] CWD /usr/www/users/xxxxxxx/xxxxxxx.com/folder
[19:02:06] Server closed connection
[19:02:06] An established connection was aborted by the software in your host machine.
[19:02:06] Transfer failed.
[19:02:06] Operation End
[19:02:17] Operation Begin
[19:02:17] CWD /usr/www/users/xxxxxxx/xxxxxxx.com/folder
[19:02:36] Server closed connection
[19:02:36] An established connection was aborted by the software in your host machine.
[19:02:36] Transfer failed.
[19:02:36] Operation End
[19:03:06] Operation Begin
[19:03:06] CWD /usr/www/users/xxxxxxx/xxxxxxx.com/folder
[19:03:25] Server closed connection
[19:03:25] An established connection was aborted by the software in your host machine.
[19:03:25] Transfer failed.
[19:03:25] Operation End


Any ideas?

Looks to me like a server issue. It closes the connection after a particular CWD command:
[19:03:06] CWD /usr/www/users/xxxxxxx/xxxxxxx.com/folder
[19:03:25] Server closed connection