connectedRouter Error: Could not find router reducer in state tree, it must be mounted under “router”

For the sake of helping future souls with this issue, it turns out that according to the linked github discussions, that version 5.0 of the history package is causing the issue and downgrading to version 4.10.1 solves the problem for me.

npm install history@4.10.1

https://github.com/ReactTraining/history/issues/803

https://github.com/ReactTraining/history/issues/804