FTP passive connection is not closed

[Andrew]

Create a binary file with contents: ff 00 00 00
Send it over FTP in passive mode, the connection hangs un-closed, thus server locks the file until timeout reaches, then Filezilla Client repeats an attempt to send the file, obviously failing as the file is locked on the server.

This is not the only file that makes filezilla hang a connection. A lot of UTF-16 files causes the same problem. Maybe all, don't know.

According to Wireshark, FTP-Data message of 4-bytes length is never followed by a FIN message, neither it is FIN itself.

Configuration:
OS: Windows 7 SP1 7601, 32bit
Filezilla: 3.5.3, build 2012-01-08
Server: Gene6 FTP Server 3.10.0 build 2

[Alexander Schuch]

FileZilla does not try to "understand" the content of a file it transfers. So I do not yet see the relation to UTF-16 encoding.

However, can you please provide logs: "If possible, provide the contents from the message log. To do so, you should set the program's language to English, set the debug level to 3 in the settings and restart the client. Then connect to the server, perform the action that causes problems and copy the entire log to the clipboard and attach it to the bug report.
Do not tamper with the log, leave it exactly as is. Do not obfuscate any addresses or filenames. You will most certainly remove vital information from the log if you modify it."

[Andrew]

I can not repeat the issue. It seems, it was a problem of windows OS, not filezilla.