Symptoms
There are SFTP receive location sessions that occur between Microsoft BizTalk Server, WinSCP, and SFTP server. While these sessions are active, you may notice that the shared temporary files get larger and are never released or deleted.
Note The shared temporary files are located in the BizTalk host service account temp folder.
Temporary files may remain locked when connection pooling is used. The temporary files contain directory listings and SFTP server operations. They can grow large quickly if there are many files that are listed in the polled SFTP receive location folder. Additionally, if the host eventually restarts or crashes, these files may become orphaned.
Status
Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section.
Resolution
This problem is fixed in the following cumulative update for BizTalk Server:
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Cumulative Update 7 for BizTalk Server 2016
Note This fix adds a new setting “Maximum Connection Reuse Time” in SFTP adapter, which will limit WinSCP connection life span. After Maximum Connection Reuse Time, connection will be closed and temporary files held by the underlying WinSCP session will be released or deleted.
References
For information about the service packs and cumulative update list for BizTalk Server, see the following article in the Microsoft Knowledge Base:
2555976 Service pack and cumulative update list for BizTalk Server
For more information about BizTalk Server hotfixes, see the following article in the Microsoft Knowledge Base:
2003907 Information about BizTalk hotfixes and Cumulative Update support
