BizTalk Server 2016 – WinSCP Receive Adapter seems to ignore polling interval

Hello,

I am not sure if this is a BizTalk or WinSCP issue, so I am asking here and at Microsoft Q&A.

On a customer system, two issues occur when using the BizTalk SFTP Receive Adapter (WinSCP).

1. Large files (>500 MB) are transferred multiple times before they are deleted.
   
2. In directories containing many smaller files (>1,000 files), there are occasional interruptions in data retrieval. In such cases, the Event Log shows the warning 'Session is not opened'. After restarting the BizTalk service, processing resumes.
   

We suspect that both issues have the same root cause: the Receive Adapter (or WinSCP) appears to ignore the 'Polling Interval' setting. We have multiple Receive Locations with different polling interval configurations (120 seconds, 240 seconds, 5 minutes, etc.). However, in all directories, the files are still retrieved within just a few seconds.

In the log file, it can be seen that for all Receive Locations, a directory listing ('Script: ls') is executed about every 30 seconds, 3–4 times in a row.

Does anyone have an idea what might be causing this issue? Any help would be greatly appreciated.

Technical details:

• BizTalk 2016 Standard Edition (Product version: 3.12.774.0)
  
• WinSCP version 5.19.2.0 (1.8.3.11614)
  --> We have also tested various older versions of WinSCP. Newer versions are not compatible with BizTalk 2016.
  

Sorry, I do not think we can help you with the problem here.

Okay, thank you very much for your response. I do have one follow-up question:
Who is executing the recurring directory listings ('Script: ls')? Is WinSCP invoked externally (i.e., by BizTalk) for each listing, or does BizTalk start a single WinSCP process and the directory listings then occur 'automatically' from that point on?

Your log shows that WinSCP was running for 6 minutes with long pauses between operations. So I believe BizTalk starts a single WinSCP process and uses it as it needs.