Explanation
This error indicates that the SSH client has detected a change in the server's RSA key, which is used to authenticate the server and establish a secure connection. The SSH client stores the fingerprints of the servers it has previously connected to in a file called known_hosts, which is usually located in the ~/.ssh directory.
When the SSH client tries to connect to a server, it compares the fingerprint of the server's RSA key with the one stored in the known_hosts file. If they match, the connection proceeds. If they do not match, the SSH client warns the user of a possible man-in-the-middle attack or a host key change, and aborts the connection.
The most likely cause of this error is that the deployment script has recreated the server with a new RSA key, which does not match the one stored in the known_hosts file. This can happen when a server is reinstalled, cloned, or migrated. To resolve this error, the administrator needs to remove or update the old fingerprint from the known_hosts file, and accept the new fingerprint when connecting to the server again. Alternatively, the administrator can use a tool or service that can synchronize or manage the RSA keys across multiple servers, such as AWS Key Management Service (AWS KMS) 1, Azure Key Vault 2, or HashiCorp Vault 3.