The server's host key was not found in the cache

This error message occurs when WinSCP connects to a new SSH server. Every server identifies itself by means of a host key; once WinSCP knows the host key for a server, it will be able to detect if a malicious attacker redirects your connection to another machine.


If you see this message, it means that WinSCP has not seen this host key before, and has no way of knowing whether it is correct or not. You should attempt to verify the host key by other means, such as asking the machine’s administrator.

If you see this message and you know that your installation of WinSCP has connected to the same server before, it may have been recently upgraded to SSH protocol version 2. SSH protocols 1 and 2 use separate host keys, so when you first use SSH-2 with a server you have only used SSH-1 with before, you will see this message again. You should verify the correctness of the key as before.1)

Read more about verifying host keys.

Learn also how to accept host key automatically in script.

1) The text is copy of PuTTY User Manual or was inspired by it.
  messages.txt · Last modified: by prikryl · Currently locked by: (

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