Sunday 15 February 2015

Synchronous XMLHttpRequest on the main thread is deprecated

Synchronous XMLHttpRequest on the main thread is deprecated because of its detrimental effects to the end user's experience.

If you are getting above issue, It means in Ajax call ( May be using xmlHttpRequest, jQuery.js OR prototype.js etc), Somewhere you have set following:
async: false

Never use "async: false", Because it has been deprecated.

async must be true, whether you are using core ajax, jQuery ajax OR prototype ajax etc.