thanks a lot for your swift reply. The files been transferred by WinSCP are compressed zip archives. /zip is used to create the archives. It works most of the time but every now an than we see the error situation that the archive files are received empty at the receiving server. So, not truncated but empty. Although the process of archive creation and compression did run correct and created the archive including files (i.e. the archive was not empty when passed down to WinSCP for transfer. I've uploaded a zip file containing an example of such an empty archive as it was received by the remote server (file name was "avcdr 091502-310722.zip", size 346 bytes). The zip file contains three screen shots showing that the file is indeed empty "avcdr 091502-310722.zip". Weird thing is that, as said, the creation of the zip archive on the sender's end works just fine and that files get added to the archive as they should. But every now and than the receiving server at the far end receives them for whatever reason empty.
Anyway, following the (I think) relevant snipped of the WinSCP log showing the transfer of that particular file "avcdr 091502-310722.zip", plus two more been transferred in the same session:
. 2022-07-31 09:15:08.935 File: 'C:\CdrTransfer\Temp\avcdr 091502-310722.zip' [2022-07-31T07:15:02.810Z] [2308]
. 2022-07-31 09:15:08.935 Copying "C:\CdrTransfer\Temp\avcdr 091502-310722.zip" to remote directory started.
. 2022-07-31 09:15:08.935 Binary transfer mode selected.
. 2022-07-31 09:15:08.935 Opening remote file.
> 2022-07-31 09:15:08.935 Type: SSH_FXP_OPEN, Size: 63, Number: 515
< 2022-07-31 09:15:08.935 Type: SSH_FXP_HANDLE, Size: 13, Number: 515
> 2022-07-31 09:15:08.935 Type: SSH_FXP_WRITE, Size: 2333, Number: 1030
> 2022-07-31 09:15:08.935 Type: SSH_FXP_CLOSE, Size: 13, Number: 1284
> 2022-07-31 09:15:08.935 Type: SSH_FXP_SETSTAT, Size: 59, Number: 777
< 2022-07-31 09:15:08.935 Type: SSH_FXP_STATUS, Size: 24, Number: 1030
< 2022-07-31 09:15:08.935 Status code: 0
< 2022-07-31 09:15:08.935 Type: SSH_FXP_STATUS, Size: 24, Number: 1284
< 2022-07-31 09:15:08.935 Status code: 0
. 2022-07-31 09:15:08.935 Preserving timestamp [2022-07-31T07:15:02.000Z]
< 2022-07-31 09:15:08.935 Type: SSH_FXP_STATUS, Size: 24, Number: 777
< 2022-07-31 09:15:08.935 Status code: 0
. 2022-07-31 09:15:08.935 Transfer done: 'C:\CdrTransfer\Temp\avcdr 091502-310722.zip' => '/pkg/prognosis/avcdr 091502-310722.zip' [2308]
. 2022-07-31 09:15:08.935 File: 'C:\CdrTransfer\Temp\avsmcdr 091503-310722.zip' [2022-07-31T07:15:03.873Z] [6858]
. 2022-07-31 09:15:08.935 Copying "C:\CdrTransfer\Temp\avsmcdr 091503-310722.zip" to remote directory started.
. 2022-07-31 09:15:08.935 Binary transfer mode selected.
. 2022-07-31 09:15:08.935 Opening remote file.
> 2022-07-31 09:15:08.935 Type: SSH_FXP_OPEN, Size: 65, Number: 1539
< 2022-07-31 09:15:08.935 Type: SSH_FXP_HANDLE, Size: 13, Number: 1539
> 2022-07-31 09:15:08.935 Type: SSH_FXP_WRITE, Size: 6883, Number: 2054
> 2022-07-31 09:15:08.935 Type: SSH_FXP_CLOSE, Size: 13, Number: 2308
> 2022-07-31 09:15:08.935 Type: SSH_FXP_SETSTAT, Size: 61, Number: 1801
< 2022-07-31 09:15:08.935 Type: SSH_FXP_STATUS, Size: 24, Number: 2054
< 2022-07-31 09:15:08.935 Status code: 0
< 2022-07-31 09:15:08.935 Type: SSH_FXP_STATUS, Size: 24, Number: 2308
< 2022-07-31 09:15:08.935 Status code: 0
. 2022-07-31 09:15:08.935 Preserving timestamp [2022-07-31T07:15:03.000Z]
< 2022-07-31 09:15:08.935 Type: SSH_FXP_STATUS, Size: 24, Number: 1801
< 2022-07-31 09:15:08.935 Status code: 0
. 2022-07-31 09:15:08.935 Transfer done: 'C:\CdrTransfer\Temp\avsmcdr 091503-310722.zip' => '/pkg/prognosis/avsmcdr 091503-310722.zip' [6858]
. 2022-07-31 09:15:08.935 File: 'C:\CdrTransfer\Temp\avsmcdrx 091504-310722.zip' [2022-07-31T07:15:04.919Z] [7635]
. 2022-07-31 09:15:08.935 Copying "C:\CdrTransfer\Temp\avsmcdrx 091504-310722.zip" to remote directory started.
. 2022-07-31 09:15:08.935 Binary transfer mode selected.
. 2022-07-31 09:15:08.935 Opening remote file.
> 2022-07-31 09:15:08.935 Type: SSH_FXP_OPEN, Size: 66, Number: 2563
< 2022-07-31 09:15:08.935 Type: SSH_FXP_HANDLE, Size: 13, Number: 2563
> 2022-07-31 09:15:08.935 Type: SSH_FXP_WRITE, Size: 7660, Number: 3078
> 2022-07-31 09:15:08.935 Type: SSH_FXP_CLOSE, Size: 13, Number: 3332
> 2022-07-31 09:15:08.935 Type: SSH_FXP_SETSTAT, Size: 62, Number: 2825
< 2022-07-31 09:15:08.935 Type: SSH_FXP_STATUS, Size: 24, Number: 3078
< 2022-07-31 09:15:08.935 Status code: 0
< 2022-07-31 09:15:08.935 Type: SSH_FXP_STATUS, Size: 24, Number: 3332
< 2022-07-31 09:15:08.935 Status code: 0
. 2022-07-31 09:15:08.935 Preserving timestamp [2022-07-31T07:15:04.000Z]
< 2022-07-31 09:15:08.935 Type: SSH_FXP_STATUS, Size: 24, Number: 2825
< 2022-07-31 09:15:08.935 Status code: 0
. 2022-07-31 09:15:08.935 Transfer done: 'C:\CdrTransfer\Temp\avsmcdrx 091504-310722.zip' => '/pkg/prognosis/avsmcdrx 091504-310722.zip' [7635]
. 2022-07-31 09:15:08.935 Copying finished: Transferred: 16.801, Elapsed: 0:00:00, CPS: 0/s
> 2022-07-31 09:15:08.982 Script: exit
. 2022-07-31 09:15:08.982 Script: Exit code: 0
I've asked the admin of the receiving server to send a copy of the relevant log entries but I did not get it yet.