usebruno/bruno · error · Error

Creating a variable without specifying a name is not allowed

Error message

Creating a variable without specifying a name is not allowed.

What it means

Thrown by bru.setVar(key, value) when the key argument is falsy. This guards the runtime (request-scoped) variable scope. The check at bru.js:310 rejects undefined, null, empty string, 0, and false before validating the key format and writing to runtimeVariables.

Source

Thrown at packages/bruno-js/src/bru.js:311

      this.oauth2CredentialsToReset.push(credentialId);
    }

    // Remove matching credential variables so subsequent getOauth2CredentialVar() calls return undefined
    const prefix = `$oauth2.${credentialId}.`;
    for (const key of Object.keys(this.oauth2CredentialVariables)) {
      if (key.startsWith(prefix)) {
        delete this.oauth2CredentialVariables[key];
      }
    }
  }

  hasVar(key) {
    return Object.hasOwn(this.runtimeVariables, key);
  }

  setVar(key, value) {
    if (!key) {
      throw new Error('Creating a variable without specifying a name is not allowed.');
    }

    if (variableNameRegex.test(key) === false) {
      throw new Error(
        `Variable name: "${key}" contains invalid characters!`
        + ' Names must only contain alpha-numeric characters, "-", "_", "."'
      );
    }

    if (!Object.hasOwn(this.runtimeVariables, key) || !isEqual(this.runtimeVariables[key], value)) {
      this.runtimeVariables[key] = value;
      this._runtimeVarsDirty = true;
    }
  }

  getVar(key) {
    if (variableNameRegex.test(key) === false) {
      throw new Error(

View on GitHub (pinned to 9bdd81c7bd)

Solutions

Pass a non-empty string literal as the key: bru.setVar('userId', value).
Guard the call with a truthiness check on the key.
Use a default key when the dynamic source may be empty: bru.setVar(key || 'default', value).

Example fix

// before
for (const item of items) {
  bru.setVar(item.name, item.value); // item.name may be undefined
}

// after
for (const item of items) {
  if (item.name) {
    bru.setVar(item.name, item.value);
  }
}

Defensive patterns

Strategy: validation

Validate before calling

function isValidVarKey(key) {
  return typeof key === 'string' && key.length > 0;
}
// before calling: if (isValidVarKey(key)) bru.setVar(key, value);

Try / catch

try {
  bru.setVar(key, value);
} catch (e) {
  if (e.message.includes('without specifying a name')) {
    console.error('Runtime variable key was empty or missing');
  }
}

Prevention

Always pass a non-empty string as the key.
Guard dynamic keys from loops or response data with a truthiness check.
Use a fallback key when the source may be empty.

When it happens

Trigger: Calling bru.setVar(undefined, 'value'), bru.setVar('', 'value'), or bru.setVar(null, 'value'). This is common when the key is derived from response data that is not present or from a loop variable that is empty.

Common situations: Using a response field as the key name when the field is absent. Iterating over a list with empty entries and using each as a key. Forgetting to pass the first argument.

Related errors

AI-assisted analysis of usebruno/bruno@9bdd81c7bd (2026-08-13). Data as JSON: /api/errors/4954bbd8dfb20655. Report an issue: GitHub.