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FTPCaller Failed initialization - Unable to exchange encryption keys

  • November 18, 2025
  • 1 reply
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acclark
Contributor
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I am trying to connect to a SFTP using the FTP caller. I have followed the instructions in https://support.safe.com/hc/en-us/articles/25407554321805-Using-a-Private-SSH-key-with-FTPCaller-to-Authenticate-an-SFTP-Connection-for-FME-Form-and-FME-Flow-on-Windows-Systems and I can connect to the server using other methods (winscp, filezilla) so the new key is working. In the log (with debug enabled) I get the following:

SystemCaller: Executing 'start "" "C:\Program Files\PuTTY\pageant.exe" --encrypted C:\PPK\PrivateKey.ppk'

FTPCaller (FTPFactory): Using the 'SChannel' TLS library for HTTPS/FTPS connections
FTPCaller (FTPFactory): FTP info:   Trying ??.??.??.??:22...
FTPCaller (FTPFactory): FTP info: Connected to ??.??.??.?? (??.??.??.??) port 22
FTPCaller (FTPFactory): FTP info: Failure establishing ssh session: -5, Unable to exchange encryption keys
FTPCaller (FTPFactory): FTP info: closing connection #0
FTPCaller (FTPFactory): FTP/FTPS/SFTP transfer error: Failed initialization
SystemCaller_2: Executing 'taskkill /IM pageant.exe /F'
 

Any ideas? I kill the pageant instance to make it easier to test in succession. I have confirmed that pageant is starting up. I am developing on a VM that is inside our VPN so the firewall shouldnt be an issue either.

1 reply

acclark
Contributor
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  • Author
  • Contributor
  • November 27, 2025

I believe the issue to be the FTP server is using an older algorithm (SSH-DSS) and FME wont accept that.

 

I solved the issue by writing my own FTP caller (for lack of a better name) that will allow the older algorithms.