ExtJS Trouble-shooting

Uncaught Error: The following classes are not declared even if their files have been loaded: 'My.folder.File'. Please check the source code of their corresponding files for possible typos: 'app/folder/File.js ext-all-dev.js:9655
Ext.apply.onFileLoaded ext-all-dev.js:9655
(anonymous function) ext-all-dev.js:2953
Ext.apply.injectScriptElement.onLoadFn

This means that you required the file correctly, but that it's defined name did not match the file name. For example, if you require My.folder.File but define it like this:

Ext.define('My.folder.File2', {...});

more coming soon...