Unable to locate adb on macOS Catalina

Question

I am starting to learn how to do mobile programming with ReactNative on an android environment. I’m using MacOS Catalina and I’ve installed android studio and react-native-cli. I ran react-native init ShoppingList which passed

Downloading template, 
Copying template, 
Processing template 

but failed at Installing CocoaPods dependencies because I wasn't at the latest OS yet(I hope this is not part of the problem because I don’t have enough memory to upgrade OS)

I’ve referred to a suggestion inside this issue, which asks me to run

npm uninstall -g react-native react-native-cli
npm install -g react-native react-native-cli
react-native start --reset-cache

I’ve also deleted the node_modules and npm install at the root of the project. Then at the root of the project I ran react-native run-android.

Which gave me the following error

info Running jetifier to migrate libraries to AndroidX. You can disable it using "--no-jetifier" flag.
Jetifier found 967 file(s) to forward-jetify. Using 8 workers...
info Starting JS server...
/bin/sh: adb: command not found
info Launching emulator...
error Failed to launch emulator. Reason: No emulators found as an output of `emulator -list-avds`.
warn Please launch an emulator manually or connect a device. Otherwise app may fail to launch.
info Installing the app...

Deprecated Gradle features were used in this build, making it incompatible with Gradle 7.0.
Use '--warning-mode all' to show the individual deprecation warnings.
See https://docs.gradle.org/6.2/userguide/command_line_interface.html#sec:command_line_warnings

FAILURE: Build failed with an exception.

* What went wrong:
Could not determine the dependencies of task ':app:installDebug'.
> SDK location not found. Define location with an ANDROID_SDK_ROOT environment variable or by setting the sdk.dir path in your project's local properties file at '/Users/prashin/Test/ShoppingList/android/local.properties'.

* Try:
Run with --stacktrace option to get the stack trace. Run with --info or --debug option to get more log output. Run with --scan to get full insights.

* Get more help at https://help.gradle.org

BUILD FAILED in 2s

error Failed to install the app. Make sure you have the Android development environment set up: https://reactnative.dev/docs/environment-setup. Run CLI with --verbose flag for more details.
Error: Command failed: ./gradlew app:installDebug -PreactNativeDevServerPort=8081

Inside Android Studio, the following are installed

Android 11.0(R),
Android SDK Build-Tools, 
Android Emulator 30.2.6, 
Android SDK-Platform-Tools 30.0.5, 
Intel x86 Emulator Accelerator (HAXM installer) 7.5.1

I created a Pixel 2 Device with Release name R(API Level 30), and pressed the Play button countless times, it gives me the error of AVD Manager: Unable to locate ADB.

This is my .bash_profile file.

source ~/.profile

# Setting PATH for Python 3.7
# The original version is saved in .bash_profile.pysave
PATH="/Library/Frameworks/Python.framework/Versions/3.7/bin:${PATH}"
export PATH

export NVM_DIR="$HOME/.nvm"
[ -s "$NVM_DIR/nvm.sh" ] && \. "$NVM_DIR/nvm.sh"  # This loads nvm
[ -s "$NVM_DIR/bash_completion" ] && \. "$NVM_DIR/bash_completion"  # This loads nvm bash_completion

##
# Your previous /Users/prashin/.bash_profile file was backed up as /Users/prashin/.bash_profile.macports-saved_2019-10-23_at_18:32:04
##

# MacPorts Installer addition on 2019-10-23_at_18:32:04: adding an appropriate PATH variable for use with MacPorts.
export PATH="/opt/local/bin:/opt/local/sbin:$PATH"
export ANDROID_HOME=/Users/prashin/Library/Android/sdk
export ANDROID_SDK_ROOT=$ANDROID_HOME
export PATH="$PATH:$ANDROID_HOME/emulator:$ANDROID_HOME/tools:$ANDROID_HOME/platform-tools"
# export PATH="$PATH:/Users/$USER/Library/Android/sdk/platform-tools"
# export PATH=${PATH}:/usr/local/mysql-5.7.31-macos10.14-x86_64/bin
# Finished adapting your PATH environment variable for use with MacPorts.

And I do see an adb executable inside platform-tools according to this post.

What could I be missing here which is preventing me from running my basic application on the simulator? Do inform me if more information is needed.

Edit

A suggested solution of switching to .zprofile changed the error message instead. It got stuck at info launching emulator for 30s before producing the error below.

error Failed to launch emulator. Reason: Could not start emulator within 30 seconds..
warn Please launch an emulator manually or connect a device. Otherwise app may fail to launch.
info Installing the app...

> Task :app:stripDebugDebugSymbols UP-TO-DATE
Compatible side by side NDK version was not found.

> Task :app:installDebug FAILED
Skipping device 'emulator-5554' (emulator-5554): Device is OFFLINE.

Deprecated Gradle features were used in this build, making it incompatible with Gradle 7.0.
Use '--warning-mode all' to show the individual deprecation warnings.
See https://docs.gradle.org/6.2/userguide/command_line_interface.html#sec:command_line_warnings
27 actionable tasks: 2 executed, 25 up-to-date

FAILURE: Build failed with an exception.

* What went wrong:
Execution failed for task ':app:installDebug'.
> com.android.builder.testing.api.DeviceException: No online devices found.

* Try:
Run with --stacktrace option to get the stack trace. Run with --info or --debug option to get more log output. Run with --scan to get full insights.

* Get more help at https://help.gradle.org

BUILD FAILED in 4s

error Failed to install the app. Make sure you have the Android development environment set up: https://reactnative.dev/docs/environment-setup. Run CLI with --verbose flag for more details.
Error: Command failed: ./gradlew app:installDebug -PreactNativeDevServerPort=8081

Answer 1

Simply restarting the terminal made the trick for me...

Answer 2

With Catalina, Apple has changed the default shell to zsh. Therefore you have to rename your configuration files. .bashrc is now .zshrc and .bash_profile is now .zprofile. Move the contents of your .bash_profile to a new .zprofile file and restart your terminal. Run the app again with new environment variables in place.