Disconnected from FTP server after file uploaded and attempted to reconnect forever

My script synchronizes all files from a local folder to the root of an FTP server. The problem is it doesn't exit after it finishes the synchronization. Instead it keeps saying "Lost connection. Disconnected from server. Copying files to remote side failed." and asks me to choose whether to (A)bort or (R)econnect. If I chose (A)bort, quit the script, and run it again, the script can run and finish without any problem. But if I choose (R)econnect, the "Lost connection .... remote side failed." will appear with the (A)abort or (R)econnect for choice again.

I also tried to upload in the GUI. Same problem. Only that the "Lost connection ..." will show up as a pop-up alert box. However, I didn't have any problem uploading with FileZilla. I asked the support of the FTP server, they couldn't figure out either.

Both the script and log files are attached

Does it always fail on the same file - AdminAttendTypes_jp.asp?
Can you ever upload that file (even manually, not as a part of synchronization) without an error?

martin wrote:

Does it always fail on the same file - AdminAttendTypes_jp.asp?
Can you ever upload that file (even manually, not as a part of synchronization) without an error?

Hi, it failed on all files I tried to upload. And I did try to upload any file manually but got the same error.

For your reference, here I recorded what I did: <invalid hyperlink removed by admin>

And here's what I set in the Endurance in my preference, other than that I have kept everything as default: <invalid hyperlink removed by admin>

Here I'll try to dissect what happened when I uploaded files as shown in the video:
1. Right clicked a certain file and chose "Upload";
2. Uploaded to the root directory of the remote FTP server;
3. "Lost Connection" error alert box popped up, WinSCP tries to reconnect continuously every 1 second (as I set up in Endurance);

From now on, two scenarios would happen:
Scenario A (when uploading test1.txt): I clicked "Abort" AND MOVED the cursor a bit
a1. The Reconnect time changed to 30 seconds;
a2. I clicked "OK";
a3. WinSCP asked me to connect the FTP server again;
a4. After I logged in the FTP server, the remote directory shows the file I just uploaded (test1.txt).

Scenario B (when I uploading text2.txt and AdminAttendanceTypes_jp.asp): I clicked "Abort" BUT DID NOT move the cursor at all.
b1. The Reconnect time remains at 1 second;
b2. Immediately the remote directly refreshed and successfully listed all files I uploaded.

Again when I tried to upload using FileZilla (as well as CuteFTP, which I've been trying these days), no such issue has happened.

Can you attach a verbose FileZilla log file showing an upload?