FuelLabs/fuel-core · error · anyhow::Error

Message should not exist

Error message

Message should not exist

What it means

Duplicate guard for Messages during on-chain genesis import: replace(message.id(), &message) returned Some. A message with the same id (deterministic from sender, recipient, nonce, body and other fields) was already inserted in this batch or already exists in storage.

Source

Thrown at crates/fuel-core/src/service/genesis/importer/on_chain.rs:329

fn init_da_message(
    transaction: &mut StorageTransaction<&mut GenesisDatabase>,
    msg: TableEntry<Messages>,
    da_height: DaBlockHeight,
) -> anyhow::Result<()> {
    let message: Message = msg.value;

    if message.da_height() > da_height {
        return Err(anyhow!(
            "message da_height cannot be greater than genesis da block height"
        ));
    }

    if transaction
        .storage::<Messages>()
        .replace(message.id(), &message)?
        .is_some()
    {
        return Err(anyhow!("Message should not exist"));
    }

    Ok(())
}

View on GitHub (pinned to b9d4d170da)

Solutions

  1. Dedupe messages by message id in the genesis state and re-import.
  2. Wipe the db directory and re-run the import.
  3. Regenerate the message list from the source of truth with deduplication.

Example fix

// before: same message (same nonce + sender + body) twice
"messages": [
  { "sender": "0x...", "recipient": "0x...", "nonce": "0x1", "amount": "100", "data": "0x" },
  { "sender": "0x...", "recipient": "0x...", "nonce": "0x1", "amount": "100", "data": "0x" }
]

// after: single entry
"messages": [ { "sender": "0x...", "recipient": "0x...", "nonce": "0x1", "amount": "100", "data": "0x" } ]
Defensive patterns

Strategy: validation

Validate before calling

fn validate_message_uniqueness(
    messages: &[fuel_core::chain_config::MessageConfig],
) -> Result<(), String> {
    let mut seen = std::collections::HashSet::new();
    for m in messages {
        let id = fuel_core_types::fuel_types::MessageId::new(
            &m.sender,
            &m.recipient,
            &m.nonce,
            m.amount,
            &m.data,
        );
        if !seen.insert(id) {
            return Err(format!("duplicate message id {id} in genesis state"));
        }
    }
    Ok(())
}

Try / catch

match importer.run().await {
    Err(e) if e.to_string().contains("Message should not exist") => {
        // dedupe messages by id and re-import into clean storage
    }
    rest => rest,
}

Prevention

When it happens

Trigger: The same message listed twice in the genesis messages (same sender, recipient, nonce, and body), or import into a database that already contains those messages.

Common situations: Bridge message dumps containing replayed duplicates; snapshot concatenation without dedup; dirty db from a previous import.

Related errors

AI-assisted analysis of FuelLabs/fuel-core@b9d4d170da (2026-08-16). Data as JSON: /api/errors/216887f390c3531a. Report an issue: GitHub.