linera-io/linera-protocol · warning

bcs: {e}

Error message

bcs: {e}

What it means

decode_key's decode() runs bcs::from_bytes over the payload to reconstruct a RootKey. This error wraps the underlying BCS failure: the bytes decoded from hex fine, but they are not a valid BCS serialization of any RootKey variant. The CLI prints 'INVALID: bcs: <reason>' and keeps going.

Source

Thrown at linera-storage/src/decode_key.rs:86

            writeln!(
                out,
                "{trimmed}\tINVALID: shorter than --strip-bytes={strip}"
            )?;
            continue;
        };
        match decode(payload) {
            Ok(rendered) => writeln!(out, "{trimmed}\t{rendered}")?,
            Err(error) => writeln!(out, "{trimmed}\tINVALID: {error}")?,
        }
    }
    Ok(())
}

fn decode(bytes: &[u8]) -> Result<String> {
    if bytes.is_empty() {
        return Err(anyhow!("empty"));
    }
    let key: RootKey = bcs::from_bytes(bytes).map_err(|e| anyhow!("bcs: {e}"))?;
    Ok(format!("{key:?}"))
}

#[cfg(test)]
mod tests {
    use linera_base::{
        crypto::CryptoHash,
        identifiers::{BlobId, BlobType, ChainId},
    };
    use linera_storage::RootKey;

    use super::decode;

    fn roundtrip(key: RootKey) -> String {
        decode(&key.bytes()).expect("decode")
    }

    #[test]

View on GitHub (pinned to 6c226ddcb3)

Solutions

1. For ScyllaDB dumps, pass --scylla (shorthand for --strip-bytes 1) to drop the prepended tag byte
2. Try nearby strip offsets: --strip-bytes 0, 1, 2 — the message INVALID output tells you which decode failed, so iterate
3. Confirm the blob is actually a RootKey partition key and not an application-level key or a value blob

Example fix

# before
cat dump.txt | linera-storage-decode-key
# after
cat dump.txt | linera-storage-decode-key --scylla

match decode(payload) {
    Ok(rendered) => writeln!(out, "{}\t{}", trimmed, rendered)?,
    Err(e) => writeln!(out, "{}\tINVALID: {}", trimmed, e)?, // record and continue with the next key
}

When it happens

Trigger: Hex that is well-formed but not a RootKey: a wrong --strip-bytes offset (payload still carries the tag byte or lost a real byte), a value key or another table's partition key, or a RootKey format from an incompatible linera version.

Common situations: Forgetting --scylla when reading ScyllaDB dumps (each root key has one extra leading 0x00 byte); passing arbitrary DB keys found in rocksdb logs; schema/enum changes between versions altering the BCS layout.

Related errors

• empty
• Invalid chain description data for chain {chain_id}
• Failed to parse {spawn_mode_name} as a spawn_mode
• Failed to find address for {s}. {parse_error}
• Failed to find port for {s}. {parse_error}

AI-assisted analysis of linera-io/linera-protocol@6c226ddcb3 (2026-08-22). Data as JSON: /api/errors/f9c695f7d4d3e8ef. Report an issue: GitHub.