The topic discussion is on stackoverflow too old but FYI who want to do the quicky trick.

The default of Ajax call in Sencha is 30000 milliseconds (30 seconds)
So, you have to set a config to the default behavior in the Ext.data.proxy.Ajax, for example, 60s, like:

Ext.define('Core.data.proxy.WrapperAjax',{
    extend: 'Ext.data.proxy.Ajax',
    alias: 'proxy.wrapperAjax',
    config: {
        timeout: 60000
    }
    ...
});

or overwrite in Ext.data.Store proxy like:

Ext.define('MyApp.store.MyStore', {
    extend: 'Ext.data.Store',
    proxy: {
        ...
        timeout: 60000, 
        ...
    },
});

Ref:

• Sencha docs
• Stackoverflow

Nam Le, nready.net