What worked is Tools->Flutter->open Android module in Android studio, For me plugin flutter_email_sender was giving this error, so I copied local.properties file into it and the build become successful.
Or
Open Terminal
Run touch ~/.bash_profile; open ~/.bash_profile
export ANDROID_HOME=/Users/<macusername>/Library/Android/sdk
export ANDROID_SDK_ROOT=/Users/<macusername>/Library/Android/sdk
export PATH=$PATH:$ANDROID_HOME/tools:$ANDROID_HOME/platform-tools
Run source ~/.bash_profile
in android studio terminal