FuelLabs/fuels-ts · error · FuelError

TRANSACTION_ERROR

TRANSACTION_ERROR

Error message

${message}

What it means

Generic assertion helper used throughout the program package: assert(condition, message) throws a FuelError with code TRANSACTION_ERROR and the supplied message when condition is falsy. It is not a single error but a precondition guard; the real meaning is carried by the message argument (e.g. 'Wallet is required!' at base-invocation-scope.ts:552).

Solutions

1. Read the exact message in the thrown error to identify which assertion failed.
2. For 'Wallet is required!', pass an account when constructing the Contract: new Contract(id, abi, account).
3. Ensure all required arguments/objects are non-null before invoking the SDK method.

Example fix

// before
const contract = new Contract(id, abi, undefined as any);
await contract.functions.fn().simulate();

// after
const contract = new Contract(id, abi, unlockedWallet);
await contract.functions.fn().simulate();

// Generic precondition guard — read the message to know which assert failed.
// Example for the wallet precondition:
if (!contract.account) {
  throw new Error('Bind an account/wallet to the Contract before invoking functions.');
}

try {
  await contract.functions.fn().simulate();
} catch (e) {
  if (e instanceof FuelError && e.code === ErrorCode.TRANSACTION_ERROR) {
    // branch on e.message to handle the specific precondition
  } else throw e;
}

When it happens

Trigger: Any failed precondition routed through assert(): calling simulate()/fund without a bound account (this.program.account is undefined); passing undefined where a required object is expected; other internal invariants in the program/script packages.

Common situations: Invoking a contract function without binding a wallet/account to the contract; passing null txParameters; partial construction of an invocation scope.

Related errors

• DUPLICATED_POLICY
• GAS_LIMIT_TOO_LOW
• INVALID_POLICY_TYPE
• INVALID_TRANSACTION_INPUT
• INVALID_TRANSACTION_INPUT

AI-assisted analysis of FuelLabs/fuels-ts@b3f37c91ac (2026-08-12). Data as JSON: /api/errors/26bf222ab5e845fa. Report an issue: GitHub.

Appendix: source

Thrown at packages/program/src/utils.ts:14

import { getAllDecodedLogs, getDecodedLogs } from '@fuel-ts/account';
import type { TransactionResultReceipt, JsonAbisFromAllCalls, DecodedLogs } from '@fuel-ts/account';
import { ErrorCode, FuelError } from '@fuel-ts/errors';

import type { AbstractContract, CallConfig, InvocationScopeLike } from './types';

/**
 * @hidden
 *
 * Generic assert function to avoid undesirable errors
 */
export function assert(condition: unknown, message: string): asserts condition {
  if (!condition) {
    throw new FuelError(ErrorCode.TRANSACTION_ERROR, message);
  }
}

/**
 * @hidden
 *
 * Gets the ABI from an array of InvocationScopeLike.
 */
export function getAbisFromAllCalls(
  functionScopes: Array<InvocationScopeLike>
): JsonAbisFromAllCalls {
  return functionScopes.reduce((acc, funcScope, i) => {
    const { program, externalAbis } = funcScope.getCallConfig();

    if (i === 0) {
      acc.main = program.interface.jsonAbi;
      acc.otherContractsAbis = {};
    } else {

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