Plesk migration cannot be started if ECDSA Keys are used: Unable to log in to the source server 'source' by SSH service

Symptoms

• Migration fails to start the connection:

  CONFIG_TEXT: Unable to log in to the source server 'source' (203.0.113.2) by SSH service: administrator login and/or password are not correct. Set valid SSH credentials for the server and click "Prepare migration".

• An ECDSA key with 521 length is being used for the connection.

•  On the source server in /var/log/secure the following records can be found:

  CONFIG_TEXT: May 10 23:39:58 user sshd[4564]: Connection closed by 203.0.113.1 port 38772 [preauth]
  May 10 23:48:02 user sshd[5124]: error: key_from_blob: invalid format [preauth]
  May 10 23:48:02 user sshd[5124]: error: userauth_pubkey: cannot decode key: ecdsa-sha2-nistp256 [preauth]

Cause

This is Plesk Migrator bug with ID #PMT-4594 which is planned to be fixed in future updates.

Resolution

Follow the article to be notified when the bug is fixed - the article will be updated.

As a workaround use a key with 256 length

1. Connect to the server via SSH;

   Note: if direct SSH access to the server is not possible, contact server administrator for further assistance.

2. Create the key pair

   # ssh-keygen -t ecdsa -b 256

3. Copy the key to the Source server:

   # ssh-copy-id -i /root/.ssh/id_ecdsa.pub root@203.0.113.2

4. Restart the migration