OrchardCMS/OrchardCore · error · TypeError

@@toPrimitive must return a primitive value.

Error message

@@toPrimitive must return a primitive value.

What it means

Babel's compiled _toPrimitive helper throws this TypeError when an object defines Symbol.toPrimitive but its implementation returns an object instead of a primitive. It is bundled Font Awesome minified runtime code (conflict-detection.js), part of its ES-class shims.

Solutions

1. Ensure Symbol.toPrimitive implementations return a primitive (string, number, or symbol)
2. Remove/fix conflicting polyfills that redefine Symbol.toPrimitive behavior
3. Verify the Font Awesome bundle version matches other bundled Babel helpers on the page

Example fix

// before
obj[Symbol.toPrimitive] = function () { return {}; };
// after
obj[Symbol.toPrimitive] = function () { return String(this.label); };

function hasValidToPrimitive(o) { return typeof o !== 'object' || o === null || typeof o[Symbol.toPrimitive] !== 'function' || ['string','number','symbol'].includes(typeof o[Symbol.toPrimitive]('default')); }

function returnsPrimitive(v) { const r = typeof v?.[Symbol.toPrimitive] === 'function' ? v[Symbol.toPrimitive]('default') : v; return ['string','number','symbol','bigint','boolean'].includes(typeof r) || r === null; }

try { doKeyConversion(obj); } catch (e) { if (e instanceof TypeError && e.message.includes('toPrimitive')) console.error('Symbol.toPrimitive must return a primitive', obj); }

When it happens

Trigger: Calling _toPropertyKey/_toPrimitive (e.g. computed property or spread of an object) where t[Symbol.toPrimitive](hint) returns an object such as {} or an array instead of string/number/symbol.

Common situations: Malformed polyfill or monkey-patched Symbol.toPrimitive; incompatible polyfill versions on the page overriding built-ins; a custom object with a buggy toPrimitive passed where a key is expected.

Understand the failure class

Background: Type mismatch errors: IllegalArgumentException, TypeError and type guards across 150 open-source libraries — this error's family across 150 libraries.

Related errors

• @@toPrimitive must return a primitive value.
• @@toPrimitive must return a primitive value.
• Super expression must either be null or a function
• @@toPrimitive must return a primitive value.
• Invalid attempt to destructure non-iterable instance. In…

AI-assisted analysis of OrchardCMS/OrchardCore@4306c0717f (2026-09-13). Data as JSON: /api/errors/0506942e78b488b6. Report an issue: GitHub.

Appendix: source

Thrown at src/OrchardCore.Modules/OrchardCore.Resources/wwwroot/Vendor/fontawesome-free-6.7.2/js/conflict-detection.js:47

  }
  function _objectSpread2(e) {
    for (var r = 1; r < arguments.length; r++) {
      var t = null != arguments[r] ? arguments[r] : {};
      r % 2 ? ownKeys(Object(t), !0).forEach(function (r) {
        _defineProperty(e, r, t[r]);
      }) : Object.getOwnPropertyDescriptors ? Object.defineProperties(e, Object.getOwnPropertyDescriptors(t)) : ownKeys(Object(t)).forEach(function (r) {
        Object.defineProperty(e, r, Object.getOwnPropertyDescriptor(t, r));
      });
    }
    return e;
  }
  function _toPrimitive(t, r) {
    if ("object" != typeof t || !t) return t;
    var e = t[Symbol.toPrimitive];
    if (void 0 !== e) {
      var i = e.call(t, r || "default");
      if ("object" != typeof i) return i;
      throw new TypeError("@@toPrimitive must return a primitive value.");
    }
    return ("string" === r ? String : Number)(t);
  }
  function _toPropertyKey(t) {
    var i = _toPrimitive(t, "string");
    return "symbol" == typeof i ? i : i + "";
  }

  let _WINDOW = {};
  let _DOCUMENT = {};
  try {
    if (typeof window !== 'undefined') _WINDOW = window;
    if (typeof document !== 'undefined') _DOCUMENT = document;
  } catch (e) {}
  const {
    userAgent = ''
  } = _WINDOW.navigator || {};
  const WINDOW = _WINDOW;

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