Thank you for you reply.
Unfortunately, the code is too long and I don't know what to show you.
By the way, with debug running, it gets no error.
I don't understand because it works great when tested on the device.
Is it possible that app causes errors after being a package?
Well, anything is possible, but just being packaged shouldn't usually cause an app to stop working. That said, I'm not familiar enough with the Windows packaging process to know for sure.
Does your app startup depend on establishing a connection to a server? Perhaps a certificate issue is going on. I know Android debug builds and release builds vary greatly wrt how they handle SSL. Might be worth looking at.
When you're testing on the device, are you testing a full release build? Then you're sending those exact bits on to the App store, where they start failing? Did you uninstall the app from your phone entirely before installing the app store version?