FuelLabs/fuels-ts · error · FuelError

INVALID_TRANSACTION_OUTPUT

INVALID_TRANSACTION_OUTPUT

Error message

Invalid transaction output type: ${type}.

What it means

Thrown by OutputCoder.encode() when output.type is not one of OutputType (Coin=0, Contract=1, Change=2, Variable=3, ContractCreated=4). The encode switch falls through to default. It indicates an output object with an out-of-range type.

Solutions

1. Use the OutputType enum and SDK output factories when constructing outputs.
2. Validate output.type is one of the five known OutputType values before encoding.
3. Upgrade @fuel-ts/transactions if a newer output type is required.

Example fix

// before
const out = { type: 7, ... };

// after
import { OutputType } from '@fuel-ts/transactions';
const out = { type: OutputType.Coin, ... };

import { OutputType } from '@fuel-ts/transactions';

const VALID_OUTPUT_TYPES = new Set([OutputType.Coin, OutputType.Contract, OutputType.Change, OutputType.Variable, OutputType.ContractCreated]);
outputs.forEach(o => { if (!VALID_OUTPUT_TYPES.has(o.type as OutputType)) throw new Error(`Bad output type ${o.type}`); });

import { OutputType } from '@fuel-ts/transactions';
function isValidOutput(o: { type: number }): boolean {
  return [OutputType.Coin, OutputType.Contract, OutputType.Change, OutputType.Variable, OutputType.ContractCreated].includes(o.type as OutputType);
}

try {
  outputCoder.encode(value);
} catch (e) {
  if (e instanceof FuelError && e.code === ErrorCode.INVALID_TRANSACTION_OUTPUT) {
    // coerce output.type to a valid OutputType enum member before retrying
  } else throw e;
}

When it happens

Trigger: Manually constructing an Output with an invalid type number; assigning type: 5+; building transaction outputs from unvalidated external data.

Common situations: Hand-assembling outputs instead of using SDK helpers; protocol/SDK version mismatch introducing a new output kind; off-by-one type assignments.

Related errors

• INVALID_POLICY_TYPE
• INVALID_TRANSACTION_INPUT
• UNSUPPORTED_TRANSACTION_TYPE
• DUPLICATED_POLICY
• GAS_LIMIT_TOO_LOW

AI-assisted analysis of FuelLabs/fuels-ts@b3f37c91ac (2026-08-12). Data as JSON: /api/errors/225dc37d20f946c2. Report an issue: GitHub.

Appendix: source

Thrown at packages/transactions/src/coders/output.ts:293

      }
      case OutputType.Contract: {
        parts.push(new OutputContractCoder().encode(value));
        break;
      }
      case OutputType.Change: {
        parts.push(new OutputChangeCoder().encode(value));
        break;
      }
      case OutputType.Variable: {
        parts.push(new OutputVariableCoder().encode(value));
        break;
      }
      case OutputType.ContractCreated: {
        parts.push(new OutputContractCreatedCoder().encode(value));
        break;
      }
      default: {
        throw new FuelError(
          ErrorCode.INVALID_TRANSACTION_OUTPUT,
          `Invalid transaction output type: ${type}.`
        );
      }
    }

    return concat(parts);
  }

  decode(data: Uint8Array, offset: number): [Output, number] {
    let decoded;
    let o = offset;

    [decoded, o] = new NumberCoder('u8', { padToWordSize: true }).decode(data, o);
    const type = decoded as OutputType;
    switch (type) {
      case OutputType.Coin: {
        [decoded, o] = new OutputCoinCoder().decode(data, o);

View on GitHub (pinned to b3f37c91ac)