App Dies On Startup (connection to the server was unsuccessful) 

I have an Android application that I'm writing using PhoneGap BUILD. The app was working fine earlier, but now it seems I am getting this error after refining my app (some UI changes only)

1) When I start the app I (usually) get: 

**Application Error - The connection to the server was unsuccessful. 
(file:///android\_asset/www/index.html)** 

Sorry if this is duplication of any question. I have seen some similar questions here, but i couldn't find a perfect answer or solution. As in my case it was working fine until my last changes.