Application main has not been registered

Question

I have recently started to convert my react native app and running on Expo so i could test this on my actual android device. I am getting this error above. I have since then

Answer 1

I created a Project from "Doco", and save it with Practice. so write that line like that

AppRegistry.registerComponent('Practice', () => FixedDimensionsBasics);

then I get an error like in a question

So, I check on my Appdelegate.m file on ios folder and find that Project name is Project so I change that line with

AppRegistry.registerComponent('Project', () => FixedDimensionsBasics);

and my Error solved

so if you are using "Doco" then check that thing.

Answer 2

The following solution worked:

AppRegistry.registerComponent('main',() => App);

Credits: Rishav Kumar

(Cannot you people just reply to mark as solve ?)

Answer 3

Removed node_modules and reinstalled by yarn that worked for me.

Answer 4

The problem is you haven't opened your project in Android Studio. The previous project is running in android studio and you are running the latest one in emulator.

Answer 5

I came across this issue because I had previously run a React project that was not fully shut down. To fix this, I could have restarted my computer. But I chose to do this instead: (Using MacOS, should work with Linux as well, for Windows you would likely need to use Task Manager or similar):

1. Open terminal
2. Find the program that is using port 8081 by typing "lsof -i :8081". (Note this is LSOF in lowercase)
3. Look at the process ID (under the PID column)
4. Kill the process by typing "kill -9 PID" (where PID is the process ID number you found in step 3).

After killing the process you should be able to run your react-native project.