The Hetzner cutover broke WAL archiving and base backups with
InvalidArgument: barman requests SSE-S3 (encryption: AES256), but
Hetzner Object Storage supports only SSE-C, which the barman-cloud
plugin cannot use (cnpg plugin-barman-cloud #646). Confirmed live —
aws-cli PUT --sse AES256 fails the same way, plain PUT succeeds.
Remove encryption from wal/data so backups use no SSE header. Trade-off
(accepted): CNPG backups are not encrypted at rest on Hetzner; transit
is TLS and the bucket is private. Revisit if/when the plugin gains SSE-C.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>