Topic "Lost connection every 19 seconds"

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davids
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Joined: 2009-10-12
Posts: 16
I have a file that I transmit to a remote server daily, and have done so for about 6 months. It seemed to work fine for a while, but just lately I'm having a real problem with the connection dropping and reconnecting, about every 19 seconds! I assume the file has been increasing in size, it is now about 93K.

I'm not aware of any changes on our side, other than routine updates from Microsoft. I have no visibility into changes to the remote server.

I'm hoping someone can help with this, it is causing errors in the copied file, and I'm losing hair rapidly!

I've attached a full log.

Here are the logged errors that repeat each time:
Network error: Software caused connection abort
Fatal error while disposing the SFTP queue.
Connection was lost, asking what to do.
Asking user:
Software caused connection abort ()
Network error: Software caused connection abort

WinSCP version: 5.7.5
Windows version: Server 2008 R2
Transfer protocol: SFTP
Automation (command in log)
FrequentDisconnectionsExample.zip (5.41 KB) [Download]

Description: (none)

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davids
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Joined: 2009-10-12
Posts: 16
Another question I have is if there is any way to determine why the command line transfer of the file is taking so long in the first place? I tried copying the same file from the GUI, and it appeared to copy in less than a second with no problem at all.
martin
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Joined: 2002-12-10
Posts: 24555
Location: Prague, Czechia
Can you try to upgrade to 5.8.3 RC?
davids
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Joined: 2009-10-12
Posts: 16
prikryl wrote:
Can you try to upgrade to 5.8.3 RC?


I've upgraded to 5.8.3 RC, but I won't have results until tomorrow.
davids
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Joined: 2009-10-12
Posts: 16
Martin, now it seems even worse... After I upgraded to 5.8.3 RC, I had a transmission that took 1.5 hours to send a 97k file, with 201 disconnections!

Log attached (private)
FrequentDisconnects20160507.zip (70.18 KB) Private file

Description: (none)

martin
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Location: Prague, Czechia
Sorry, I have no idea, what the problem can be.
davids
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Joined: 2009-10-12
Posts: 16
This was a case of "if something seems to be the case, keep digging even if people say it isn't".

Turned out to be an out-of-control process on the remote side. The process was intended to move files out of the destination folder to be processed. It was SUPPOSED to only move a particular filename (ignore all others), and also to only even look for files every five minutes or so.

The reality was it would move any file it found, and it would start trying to move the file about 19 seconds or so after it appeared! So what was happening was this:
1. We start transmitting the file, causing the file to appear in the destination folder.
2. The remote side immediately (within 19 seconds or so) moves the file fragment to another location.
3. Our session, seeing the target file suddenly gone, assumes the connection was broken, and it attempts to reconnect.
4. That was successful, so file transmission continues.
5. The file disappears again
6. and so on.

After we got the remote site to leave the stupid file alone and let us transmit it, it started working perfectly!
martin
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Posts: 24555
Location: Prague, Czechia
Thanks for your feedback.
davids
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Joined: 2009-10-12
Posts: 16
Well, I may have spoken too soon...

I've confirmed that the remote side has configured to not touch the file until it has been present for 5 minutes - which should be plenty of time to transmit.

And some of the time that works.

But other times it starts transmitting, then just seems to stop, and then I get the same messages in the log:
Network error: Software caused connection abort
Fatal error while disposing the SFTP queue


Martin, in the first log message, which "Software" is it referring to? Is that WinSCP? I understand that these two messages are saying that the transmission was interrupted, but is there any way to know which end caused the interruption?

Thanks!
martin
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Location: Prague, Czechia
davids wrote:
Martin, in the first log message, which "Software" is it referring to? Is that WinSCP? I understand that these two messages are saying that the transmission was interrupted, but is there any way to know which end caused the interruption?

The "software" here usually means "Windows OS", see
https://winscp.net/eng/docs/message_software_caused_connection_abort#in_a_middle_of_session
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