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SSH Connection Failure After Debian 12 Migration The error in your logs is clear:

Found invalid signature alg ecdsa-sha2-nistp256 for key ID=mon_id host key

followed by:

Server at *** presented unverified EdDSA key: SHA256:REMZsrxB2MhTbBflTboABoJbMJQTLb6HKMqV/uSHdFk

What's happening When the server was migrated to Debian 12, the SSH host keys changed. Specifically: 1. The server's host key changed — Debian 12 likely now presents an EdDSA (Ed25519) host key instead of (or in addition to) the previous ECDSA key. Airbyte's SSH client (

apache-sshd

) is rejecting the new key because it doesn't match what it previously trusted. 2. Certificate signature algorithm mismatch — The

ecdsa-sha2-nistp256

signature is being flagged as invalid during the key exchange handshake. What to try The knowledge sources do not contain a specific documented fix for this exact scenario (host key change after OS migration), but based on the error pattern, here are the most relevant steps: 1. Re-test/re-save your source connection in Airbyte — Since the server's host key fingerprint changed, Airbyte may need to re-accept the new host key. Try editing your MySQL source connector and clicking "Test the source" again to see if it prompts re-acceptance. 2. Check your SSH key type — Airbyte's MySQL SSH tunnel officially supports RSA private keys (beginning with

-----BEGIN RSA PRIVATE KEY-----

). [SSH Tunnel Docs] If your bastion/jump server on Debian 12 is now configured differently, ensure you are using an RSA key for authentication. 3. Verify the bastion server's SSH configuration — Debian 12 may have changed the default host key algorithms or disabled certain algorithms. Check that the SSH server on the bastion is still configured to accept the key type Airbyte uses. 4. Check for a known SSH rekey/session issue — There is a known bug where SSH session issues (including key exchange problems) cause Airbyte syncs to fail. [SSH Rekey Issue] This may be related if the new Debian 12 server has different cipher/algorithm defaults. Important caveat The knowledge sources do not explicitly document a resolution for the specific

Found invalid signature alg ecdsa-sha2-nistp256

error after a server OS migration. I'd recommend: • Filing a bug or checking the Airbyte GitHub issues for this specific

apache-sshd

error with Debian 12. • Contacting Airbyte support if you are on Airbyte Cloud, as this appears to be a connector-level SSH client compatibility issue with the new server's host key configuration. 👍 0 button 👎 0 button ℹ️ Tip: Mention @kapa.ai in the thread for follow-ups or DM the app for 1-to-1 help.