I assume you're using Qlik Sense Enterprise?
When you have a reload of an app, a task is generated (Start->Tasks) and you'll see the task status, one of which I assume is failed?
To the right of the status there is a small information icon, if you click on this it will show you more information and allow you to download the log files that will show you the same type of logging detail as though you were running the app on the desktop.
Also - check your data connections. If they are folders, perhaps they are still showing the connection string based upon the device the app was created upon?
Start -> Data Connections.
I hope that helps?