You can try debugging the app using logcat so that log file is available to you.
Then you can find out in logs what exactly is the error
I was running into a similar issue, and I was able to fix this by updating the config.json file in the root directory with the correct runtimeUrl value.
For some reason my runtimeUrl had a ‘/’ after .com (ie appname.com/), and that was causing the issue.
After I updated the url to just be appname.com it worked fine.
Hope this helps!