FuelLabs/sway · error

Invalid salt format: {}

Error message

Invalid salt format: {}

What it means

When forc add inserts a contract dependency into Forc.toml's [contract-dependencies], the optional salt is converted via HexSalt::from_str; failure is wrapped as 'Invalid salt format'. The underlying causes are exactly the two wrapped errors from manifest/mod.rs: a salt not starting with 0x, or a 0x-prefixed body that is not exactly 64 hex characters (32 bytes).

Source

Thrown at forc-pkg/src/manifest/dep_modifier.rs:323

            doc[&section_name] = Item::Table(Table::new());
        }

        let table = doc[section_name.as_str()].as_table_mut().unwrap();

        match self {
            Section::Deps => {
                let item = match dep_data {
                    Dependency::Simple(ver) => ver.to_string().into(),
                    Dependency::Detailed(details) => {
                        Item::Value(toml_edit::Value::InlineTable(generate_table(&details)))
                    }
                };
                table.insert(&dep_name, item);
            }
            Section::ContractDeps => {
                let resolved_salt = match salt.as_ref().or(salt.as_ref()) {
                    Some(s) => {
                        HexSalt::from_str(s).map_err(|e| anyhow!("Invalid salt format: {}", e))?
                    }
                    None => HexSalt(fuel_tx::Salt::default()),
                };
                let contract_dep = ContractDependency {
                    dependency: dep_data,
                    salt: resolved_salt.clone(),
                };

                let dep = &contract_dep.dependency;
                let salt: &HexSalt = &contract_dep.salt;
                let item = match dep {
                    Dependency::Simple(ver) => {
                        let mut inline = InlineTable::default();
                        inline.insert("version", Value::from(ver.to_string()));
                        inline.insert("salt", Value::from(format!("0x{salt}")));
                        Item::Value(toml_edit::Value::InlineTable(inline))
                    }
                    Dependency::Detailed(details) => {

View on GitHub (pinned to 47e5e902fa)

Solutions

1. Format the salt as 0x + 64 hex chars, e.g. 0x0000000000000000000000000000000000000000000000000000000000000000 for the default.
2. Omit --salt entirely to get the default zero salt (HexSalt(fuel_tx::Salt::default()) in the source).
3. Strip surrounding quotes/whitespace the shell may have preserved in the value.

Example fix

# before
$ forc add --contract-dependency mydep --salt deadbeef

# after
$ forc add --contract-dependency mydep --salt 0x00000000000000000000000000000000deadbeef000000000000000000000000

// Rust, pre-check a --salt value before the DepModifier runs:
fn valid_hex_salt(s: &str) -> bool {
    let body = s.strip_prefix("0x").unwrap_or("");
    body.len() == 64 && body.chars().all(|c| c.is_ascii_hexdigit())
}

// anyhow Result from the dep-modifier flow; catch and restate format:
match add_contract_dep(...) {
    Err(e) if e.to_string().contains("Invalid salt format") =>
        eprintln!("salt must be 0x + 64 hex chars, or omitted"),
    other => other.unwrap(),
}

When it happens

Trigger: forc add --contract-dependency dep --salt <value> (or the programmatic equivalent calling the DepModifier insert API) where value is not 0x followed by 64 hex characters.

Common situations: Passing an EVM-style salt with different length; copying a salt with whitespace/quotes from a terminal; forgetting the 0x prefix; using a short placeholder like 0x0.

Related errors

• invalid salt in lock file: {e}
• missing dependency name
• invalid version requirement `{v}`
• the dependency `{}` could not be found in `{}`
• hex salt declaration needs to start with 0x

AI-assisted analysis of FuelLabs/sway@47e5e902fa (2026-08-16). Data as JSON: /api/errors/42b50e30214b7775. Report an issue: GitHub.