Trouble connecting to SFTP server from webmethods IS

Hi All,

Can anyone help me in resolving the below issue please?

[ISS.0147.9010] Cannot get host key from server []:22. Details: com.jcraft.jsch.JSchException: Session.connect: Prime size must be multiple of 64, and can only range from 512 to 1024 (inclusive)

Facing this error while trying to create a SFTP server alias ang generating a host key.

Hi Sangamesh,

please provide your wM version as well as the Fixes applied to your IS installation.

There have been some issues to the SFTP JCraft lib with retrieving the keys from the server for which Fixes exist.
Please check with UpdateManager if there are Fixes available for your version.
If yes, then apply these and test again.


Hello Holger,

We are currently on WM9.7 version and fixes applied when IS installation is IS_9.7_SPM_Fix1.

Can you please guide how to get those fixes and apply?

Hi Sangamesh,

hopefully you have an Empower account with download rights for your company.
In this case you can install/open UpdateManager (SUM) and select the fixes you need.
Fixes for SFTP issues are part of IS_Core as well as SCG, TPP and TPS fixes.
IS_SPM Fix is not involved here.


if you have access to a newer version of WM (10.1 , 10.5 etc), try to connect from there. The supported algorithm in 9.7 is pretty outdated.

Thanks Holger,

I have some doubts. What is this Host Key and from where this is generated?

We have other SFTP connections working fine in our webMethods. Issue is only with this SFTP.

Hi Sangamesh,

in this case you should get in contact with the admins of the sftp server.
The host key is a generated ssh-rsa key (i.e. by ssh-keygen) provided by the host of the SFTP-Server.


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