Created App crashes at launch in mobile phone

[ans]

I have created a simple relay on/off app using google firebase. When I installed it successfully gets installed in mobile phone but when I launch it crashes & closes immediately without any error.
I have a similar app using firebase with 4 relays on/off developed by another person. When I use his .aia file to download .apk from the app inventor site, it does not crash in the phone after launch but when I just change firebaseDB token & URL in his .aia file and then install in the phone, then it crashes immediately without any error.
What could be the possible remedy for this problem?

Thanks

[dora_paz]

Is firebase's location set to us-central ? Try to create another project in firebase and set location to us-central1

[Gordon_Lu]

Also, you are reminded with the following warning when you add a FirebaseDB component:

FirebaseDB is an experimental feature which may change in the future or break. Packaged Apps built with this component may not function into the indefinite future.

[ans]

Thank you very much @dora_paz ! I had chosen Singapore server in previous try. Now I have changed server location to US-central & my app is not crashing anymore.
Thanks again.