4.0.0-beta.30
react-native 0.55.3
I am facing the issue #2808
so I upgraded my router-flux version from 0.27 to 0.30
now facing the issue #2865 is there any proper documentation for this issues

Try to remove the dependency and add it again.
yarn remove react-native-router-flux || npm remove react-native-router-flux
yarn add react-native-router-flux || npm install react-native-router-flux
It works for me.
I've been having this issue every since I updated react native as well. This is a widespread issue all over github for react-navigation. No clue how to fix it I've tried everything.
EDIT: I reinstalled/updated react native, linked the packages, and npm removed and install router flux and it began working again. I believe the problem lies if you update router flux past 0.28
I solved my issue by removing ^ from the _package.json_
"react-native-router-flux": "4.0.0-beta.27",
so I am closing it
Most helpful comment
Try to remove the dependency and add it again.
yarn remove react-native-router-flux || npm remove react-native-router-flux
yarn add react-native-router-flux || npm install react-native-router-flux
It works for me.