What causes "Failed to load the contract" in FuelLabs/fuels-rs?

Build the contract: forc build --release so the binary exists at the path passed to the macro

Failed to load the contract

Error message

Failed to load the contract

What it means

For each contract declared in setup_program_test!, the generated code calls Contract::load_from(bin_path, load_config) synchronously and expects success. The panic means the compiled contract binary could not be read or parsed: the file is missing, empty, or not a valid fuel binary.

Source

Thrown at packages/fuels-macros/src/setup_program_test/code_gen.rs:155

                    // These lines must be inside the `quote!` macro, otherwise the salt remains
                    // identical between macro compilation, causing contract id collision.
                    ::fuels::test_helpers::generate_random_salt()
                }
            } else {
                quote! { [0; 32] }
            };

            quote! {
                let salt: [u8; 32] = #salt;

                let #contract_instance_name = {
                    let load_config = ::fuels::programs::contract::LoadConfiguration::default().with_salt(salt);

                    let loaded_contract = ::fuels::programs::contract::Contract::load_from(
                        #bin_path,
                        load_config
                    )
                    .expect("Failed to load the contract");

                    let response = loaded_contract.deploy_if_not_exists(
                        &#wallet_name,
                        ::fuels::types::transaction::TxPolicies::default()
                    )
                    .await
                    .expect("Failed to deploy the contract");

                    #contract_struct_name::new(response.contract_id, #wallet_name.clone())
                };
            }
        })
        .reduce(|mut all_code, code| {
            all_code.extend(code);
            all_code
        })
        .unwrap_or_default()
}

View on GitHub (pinned to d9a250a518)

Solutions

Build the contract: forc build --release so the binary exists at the path passed to the macro
Verify the path string and that the .bin file is non-empty
Wire CI (or a justfile/build.rs) to run forc build before cargo test

Example fix

# before
cargo test # panics: "Failed to load the contract" — binary missing

# after
forc build --release
cargo test

Defensive patterns

Strategy: validation

Validate before calling

// Fail fast when the contract binary is missing before deployment-heavy tests
let bin = "tests/contracts/my_contract/out/release/my_contract.bin";
assert!(
    std::path::Path::new(bin).exists(),
    "contract binary missing — run `forc build --release` first"
);

Try / catch

// In manual setup code, propagate instead of expecting:
let loaded = Contract::load_from(bin, LoadConfiguration::default())
    .with_context(|| format!("failed to load contract binary at {bin}"))?;

Prevention

Run forc build --release before cargo test (wire it into CI or a justfile)
Assert binary existence in a lightweight pre-test
Keep contract paths in one place to avoid typos

When it happens

Trigger: The bin path given in the macro (e.g. "tests/contracts/my_contract/out/release/my_contract.bin") does not exist because forc build was never run, or the .bin file is corrupt/empty.

Common situations: Running cargo test before building contracts; typo in the contract path; CI pipelines that skip the forc build step.

Related errors

AI-assisted analysis of FuelLabs/fuels-rs@d9a250a518 (2026-08-16). Data as JSON: /api/errors/80c2c3d3996f4983. Report an issue: GitHub.