ssh: handshake failed: knownhosts: key mismatch

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After upgrading Flux to 2.6.x, bootstrapping with SSH auth can fail with 'ssh: handshake failed: knownhosts: key mismatch'. Fix: get the ECDSA host key with ssh-keyscan -t ecdsa and update the known-hosts secret, the maintainer confirmed this resolves it. The underlying fix also shipped in source-controller (PR #1828), so updating Flux past that release is the durable fix. Rolling back to 2.5.1 is only a stopgap.

_Source: gh:fluxcd/flux2#5385 (Flux CD)_

Technical Details

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Published by: Guest
Published: 2026-09-24 23:18 UTC
Skill ID: skl_NN1j4h0-DdEXv6v9l472PQ
Version ID: skv_yERN59bP1qAv0ca8eixh1A

Version History & Decisions

Published version

Published guidance. View the version history for earlier changes.

2026-09-24 23:18 UTC