WinscpDLL detecting timeout / failing to upload full file

Hello.

Im using a vb.net console app that has been working for many years now. However, since the 12th October 2019 - uploading a normal fUll size file to a 3rd party has suddenly stopped working.

I have checked the 3rd party, and our ISP, whom both report nothing their side has changed.

I can run the app that uses 5.7 version of the WinscpDLL and the latest 5.16 version, locally, and it sends a full file, however, server side in our data centre.. it fails to upload full files (a file with more than 19 lines of data)

I can connect via the winscp Client GUI and it sends as normal, but via the DLL. does not send..
I have tried raw settings and config settings sendbuf=0, have tried different versions of the client and dll, but does not work server side.. again have checked all configs server side for ourselves and the 3rd party. but still the DLL does not send full files, as it detects timeouts.

I have tried so far:
- raw settings and config settings in the VB.net code to sendbuf=0
- different timeouts
- and different servers.

App is run from main adminstrator account and NOT an IIS Web user account.
I am at a loss as to what it could be, hopefully someone on here has experienced the same issues.

Windows 2008 Datacentre using a vb.net app via the administrator account on a scheduled task.

I have included the latest debug and session logs.

Any help greatly appreciated.

cybordax wrote:

I have tried so far:
...
- and different servers

Local servers (where WinSCP runs) or remote servers (where it connects to)?

Do you get the problem even if you do not enable verbose logging?

martin wrote:

cybordax wrote:

I have tried so far:
...
- and different servers

Local servers (where WinSCP runs) or remote servers (where it connects to)?

Do you get the problem even if you do not enable verbose logging?

Hello
Thanks for the reply - I get the symptoms on the remote server I connect to, regardless of verbose logging or not.

Same app and same code runs perfectly fine on my local PC, same app same code, server side, anything more than 19 lines in a file, (txt file) and it times out.
Both ISP and 3rd party whom we connect to, says there are no limitations or restrictions on their servers, or firewalls etc.

I am a tad stumped on this one.

Thanks for your report.
I have sent you an email with a debug version of WinSCP to the address you have used to register on this forum.

Hello
I have not had the opportunity to look at this yet, from the debug version you provided me, due to work commitments.

I hope to look at this over the Christmas holidays

Hello Martin - I have sent you a direct email with the debug file attached as a zip file.

Please let me know if you are still ok to look into this for me.

Cheers