FileZilla restarts download after intermittent connection problem

[trtz]

Repro:

1. Start a big file download.
2. Reboot the server to force the connection to drop. I used a Windows 2012 R2 IIS FTP site and rebooted the entire machine.
3. Observe, that the file transfer starts anew. This is a problem if the file takes a few days to download. A lot of progress is lost.

Note, that the typical dialog asking the user how to resolve a conflict (skip, overwrite, resume, ...) did not appear.

Desired behavior: Ask the user or simply resume the file download.

The Filezilla log showed the following during the connection outage:

Some earlier connection problem that apparently was resolved by restarting:

Command: RETR FILENAME
Response: 150 Opening BINARY mode data connection.
Response: 226 Transfer complete.
Command: PASV
Response: 227 Entering Passive Mode (IP,216,163).
Command: REST 50930845561
Response: 350 Restarting at 50930845561.
Command: RETR FILENAME
Response: 150 Opening BINARY mode data connection.
Error: Disconnected from server: ECONNABORTED - Connection aborted
Error: File transfer failed after transferring 2 GB in 39888 seconds
Status: Resolving address of HOSTNAME
Status: Connecting to IP:PORT...
Status: Connection established, waiting for welcome message...
Status: Insecure server, it does not support FTP over TLS.
Status: Connected
Status: Starting download of PATH/FILENAME
Status: Testing resume capabilities of server
Command: TYPE I
Response: 200 Type set to I.
Command: PASV

...
A few hours later the server reboot:

Command: RETR FILENAME
Response: 150 Opening BINARY mode data connection.
Error: Could not read from transfer socket: ECONNRESET - Connection reset by peer
Error: Connection timed out
Error: File transfer failed after transferring 8 GB in 3380 seconds
Status: Resolving address of HOSTNAME
Status: Connecting to IP:PORT...
Error: Connection timed out
Error: Could not connect to server
Status: Delaying connection for 5 seconds due to previously failed connection attempt...
Status: Resolving address of HOSTNAME
Status: Connecting to IP:PORT...
Error: Connection timed out

These messages were repeated a lot. Lots of retries. Now Filezilla gives up to restart:

Status: Connecting to IP:PORT...
Status: Connection established, waiting for welcome message...
Status: Insecure server, it does not support FTP over TLS.
Status: Connected
Status: Starting download of PATH/FILENAME
Status: Testing resume capabilities of server
Command: TYPE I
Response: 200 Type set to I.
Command: PASV
Response: 227 Entering Passive Mode (IP,192,4).
Command: REST 162230556159
Response: 350 Restarting at 162230556159.
Command: RETR FILENAME
Response: 125 Data connection already open; Transfer starting.
Response: 226 Transfer complete.
Command: PASV
Response: 227 Entering Passive Mode (IP,192,5).
Command: REST 62409403658
Response: 350 Restarting at 62409403658.
Command: RETR FILENAME
Response: 150 Opening BINARY mode data connection.
Error: Connection timed out
Error: File transfer failed after transferring 93 MB in 35 seconds
Status: Resolving address of HOSTNAME
Status: Connecting to IP:PORT...
Status: Connection established, waiting for welcome message...
Status: Insecure server, it does not support FTP over TLS.
Status: Connected
Status: Starting download of PATH/FILENAME
Status: Testing resume capabilities of server
Command: TYPE I
Response: 200 Type set to I.
Command: PASV
Response: 227 Entering Passive Mode (IP,192,13).
Command: REST 162230556159
Response: 350 Restarting at 162230556159.
Command: RETR FILENAME
Response: 150 Opening BINARY mode data connection.
Error: Connection timed out
Error: File transfer failed
Status: Resolving address of HOSTNAME
Status: Connecting to IP:PORT...
Status: Connection established, waiting for welcome message...
Status: Insecure server, it does not support FTP over TLS.
Status: Connected
Status: Starting download of PATH/FILENAME
Command: CWD PATH
Response: 250 CWD command successful.
Command: TYPE I
Response: 200 Type set to I.
Command: PASV
Response: 227 Entering Passive Mode (IP,192,14).
Command: RETR FILENAME
Error: Connection timed out
Error: File transfer failed
Status: Resolving address of HOSTNAME
Status: Connecting to IP:PORT...
Status: Connection established, waiting for welcome message...
Status: Insecure server, it does not support FTP over TLS.
Status: Connected
Status: Starting download of PATH/FILENAME
Command: CWD PATH
Response: 250 CWD command successful.
Command: TYPE I
Response: 200 Type set to I.
Command: PASV
Response: 227 Entering Passive Mode (IP,192,15).
Command: RETR FILENAME
Response: 125 Data connection already open; Transfer starting.
Error: Connection timed out
Error: File transfer failed after transferring 4 MB in 12 seconds
Status: Resolving address of HOSTNAME
Status: Connecting to IP:PORT...
Status: Connection established, waiting for welcome message...
Status: Insecure server, it does not support FTP over TLS.
Status: Connected
Status: Starting download of PATH/FILENAME

Should be easy to repro. I have had this problem many times already.

Sometimes, sleeping the client machine at night and resuming it in the morning also causes this issue.

Version: 3.10.02. Has been happening for a long time, though. Nothing new.

[Tim Kosse]

I've been unable to reproduce this issue.

Do you still experience it in 3.10.2-rc2?

Do you at any time see the message "Server does not support resume of files > 4GB." in red in the log? (Message can also contain 2GB)

The location you are downloading the file to, is it an internal harddisk or some other type of storage? E.g. network share, external USB drive or similar

[trtz]

I will run another test.