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Our file transfer automation software is connecting to an external SFTP server to download files. It's connecting using Putty's command line tool PSFTP. When it kicks off at it's scheduled time, an error results. The error is:

Remote working directory is /directory
lcd: unable to change directory: Invalid Signature.

Using username "username".
Pre-authentication banner message from server:
| IM CCaaS  FTP server
End of banner message from server

When I manually FTP to the server, I can log in with no issue. I then re-run the job and it completes successfully. I've googled this and found articles on key exchanges with similar errors, but this connection isn't using private/public keys. I cut over the application to a new Windows 2016 server on September 21st. There have been some successful transfers. I've also read the version of PSFTP may be the issue (0.73), but I would have expected consistent issues connecting. It seems sporadic. I'm not sure if the issue is on my end or at the destination. Any thoughts?

user2073183
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1 Answers1

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This is not SFTP problem. You have problem when changing a local working directory (using lcd command in the sftp client).

So this probably covers the problem:
System error 2148073478, extended error, or Invalid Signature error message on SMB connections in Windows Server 2012 or Windows 8.

Martin Prikryl
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  • I revised the command file to download the file to a local folder then run cmd.exe with the move command to move the file from the local folder to the UNC share. I set this up in test (Windows 2016) and it ran for the past five days with no issue. I implemented the changes into production and ran the process. It failed with "Invalid signature" on the move command. Ran the process again and was successful. Production is also Windows 2016. – user2073183 Oct 28 '20 at 17:32
  • I assume you mean Windows `cmd.exe` `move` command (there's no `move` command in `psftp`) – So still a *local directory* problem, not `psftp`. – Martin Prikryl Oct 28 '20 at 17:52
  • That is correct. Files are downloaded locally then a separate step runs cmd.exe with the move command. If the issue is with the third party file server, in this case the server the file is being moved to, I'm not sure why is it working consistently with the Windows 2016 test server and not the Windows 2016 prod server. I'll have to see what Secure Negotiate is set on both Win 2016 servers.... – user2073183 Oct 29 '20 at 18:47