This usually means that the user mixed up our lowercase/uppercase naming convention; see https://github.com/facebook/react/pull/3429#issuecomment-85166440.

We could add a message like

> Warning: The tag <commentBox> is unrecognized in this browser. If you meant to render a React component, start its name with an uppercase letter.

We'd check this only once per tag and only in development mode.

/**
 * Copyright 2013-present, Facebook, Inc.
 * All rights reserved.
 *
 * This source code is licensed under the BSD-style license found in the
 * LICENSE file in the root directory of this source tree. An additional grant
 * of patent rights can be found in the PATENTS file in the same directory.
 *
 * @providesModule ReactDOMFiberComponent
 * @flow
 */
'use strict';
var CSSPropertyOperations = require('CSSPropertyOperations');
var DOMNamespaces = require('DOMNamespaces');
var DOMProperty = require('DOMProperty');
var DOMPropertyOperations = require('DOMPropertyOperations');
var EventPluginRegistry = require('EventPluginRegistry');
var ReactBrowserEventEmitter = require('ReactBrowserEventEmitter');
var ReactDOMFiberInput = require('ReactDOMFiberInput');
var ReactDOMFiberOption = require('ReactDOMFiberOption');
var ReactDOMFiberSelect = require('ReactDOMFiberSelect');
var ReactDOMFiberTextarea = require('ReactDOMFiberTextarea');
var {getCurrentFiberOwnerName} = require('ReactDebugCurrentFiber');
var emptyFunction = require('fbjs/lib/emptyFunction');
var invariant = require('fbjs/lib/invariant');
var setInnerHTML = require('setInnerHTML');