Develop Reference

"Error connecting to the service protocol: failed to connect to http://..." after running adb reverse command

I have a flutter app that I debug on real device, and it runs fine in the debug mode.
I got to a point when I created a backend server that runs in a localhost:8080 only machine, so in order to make it accessible from my real phone device also, I ran:
adb reverse tcp:8080 tcp:8080
and it worked exactly as I expected where the app was running.
But, after this, if I re-rerun the app again in the real device ( unplug and plug again the USB in the machine ), it got to the point of showing the √ Built build\app\outputs\flutter-apk\app-debug.apk. and this error got thrown and it terminate/close the debug process of the app :
Error connecting to the service protocol: failed to connect to http://127.0.0.1:61410/DHX5GEb2kn4=/
I did try to kill the adb.exe command with:
adb kill-server
supposing that this will undo the adb reverse command but the same error gets thrown
well, I found a painful fix, which is restarting the device, but this takes much time and is painful.
I want to know what should I turn on/off while debugging my flutter app

I finally managed to fic the issue, and get my app debugging properly again.
What I did wrong ?
When I needed the adb, I thought it's not installed on my laptop since when I runned adb command in command line tool (cmd), it tells me that it's not recognized, so the smart me did downloaded the android platforms-tools separatly from Here
, and I runned the :
adb reverse tcp:8080 tcp:8080
from it's folder, which runned, and I thought I solved the issue, but what I just learned is that the Dart VM server uses an internal installed another adb.exe which have a different version (39) that what I run the command with (41).
so when I re-debug the flutter project, the error happens.
How did I fix it?
I did simply searched for the internal adb.exe, you can find in the Android folder, ...\Android\SDK\platforms\tools\adb.exe.
I Paste the new adb.exe with the height version inside the folder.
Run the command from that folder
For 3., you can set the path of that folder in the PATH in environment variables, so you can run the adb commands from anywhere.

Running Emulators on Different Device for React Native Applications

Since Xcode and Android studio consume a lot, I am having storage and processing capacity issues on my Mac, while developing React Native Applications.
My Question is that is there any way to run emulators (in my case android emulator) on another PC, while I am coding on Mac?
Thank you

I tried once the solution below, it might also work for you. And the source is in this repo.
If you want to write and compile an Android application on one machine and debug it remotely on the emulator launched on another follow the instructions below:
Preparation
First of all you need to install SSH server on your remote machine.
Ubuntu
You can use OpenSSH.
sudo apt install openssh-server
Windows
You can install OpenSSH on Windows following this link.
Connection
Now you must connect local machine to remote server using SSH tunnel.
The emulator listens on two TCP ports per instance: 5554 for the telnet interface and 5555 for control communication with tools like DDMS. So you could probably get away with only forwarding port 5555. Each subsequent emulator takes the next available even+odd port number tuple.
Note that you need to enter the ip address of emulator running on remote server instead of emulator-ip and also remote machine username and hostname instead of myuser and remote-server.
Ubuntu
On the local machine try:
ssh -NL 5554:emulator-ip:5554 -L 5555:emulator-ip:5555 myuser#remote-server
Windows
Follow this link instructions and add two source ports and destinations below:
Source port: 5554
Destination: emulator-ip:5554
Source port: 5555
Destination: emulator-ip:5555
then connect to remote server.
ADB
The emulator tries to notify a local adb server at startup; hence you need to restart adb in order for it to probe the local 5554+ ports.
adb kill-server; adb devices
adb devices shows a new emulator — emulator-5554 — and you can use it as if it is running on your local machine.
Running
Finally run:
react-native run-android
the app should be installed on emulator, but you may face an error:
error: more than one device/emulator
Could not run adb reverse: Command failed: path/to/sdk/adb -s emulator-5554 reverse tcp:8081 tcp:8081
you need to specify your debug host IP and port in app's Developer menu -> Dev settings -> Debug server host & port, that is your local machine ip address and 8081 for port.
Note that after APK installation you don't need to do any of these steps. You can just start the npm server: npm start in the project directory of your local machine, run the app on the emulator in remote machine and then reload.
if there was another error:
Exception in thread "Device List Monitor" java.lang.NullPointerException
try:
react-native run-android --deviceId

Android ADB: Device unauthorized trying to connect to a port-forwarded remote emulator

Background:
I recently upgraded to an AMD processor and found that the Android device emulator was complaining about not having hardware acceleration. (This is an issue for another question). My old Intel computer worked fine, so I decided to run the emulator on the old Intel PC (emu-pc) and use my new AMD computer (dev-pc) to code.
Problem:
I wasn't able to directly have the emulator expose its ports on the emu-pc to connect to via adb on the dev-pc (again an issue for another question), so I installed the Windows 10 OpenSSH server (Microsoft instructions) and connected to it from my dev-pc, forwarding the proper ADB ports:
ssh {you}#<{remote ip} -L 5554:localhost:5554 -L 5555:localhost:5555
I then tried connecting to the remote emulator via adb:
adb connect localhost
I was met with
$ ./adb devices
List of devices attached
localhost:5555 unauthorized
I've tried a few of the posts stating you should disable and re-enable USB debugging or revoke all the USB debugging authorization or use the "Wipe Data" option in the AVD Manager. None of these worked. I also tried messing with the adbkeys on the emulator under /data/misc/adb/adbkeys but I get permission denied trying to do anything to that file. (I also can't ls it via an adb shell)
Any ideas?

I found something that worked for me. I was able to telnet to the emu-pc via port 5554, where I tried to auth on the Android console. The login message said:
Android Console: type 'auth <auth_token>' to authenticate
Android Console: you can find your <auth_token> in
'C:\Users\exile57\.emulator_console_auth_token'
I found that file and was able to log in. This made me think that the emulator thinks the connection is coming from the emu-pc, yet the keys that I was using were generated on the dev-pc. I found the keys on emu-pc in C:\Users\[your user]\.android as adbkey and adbkey.pub. I copied those to the dev-pc, killed the adb server, disconnected all devices, then tried reconnecting:
$ ./adb disconnect
./adb kill-server
./adb connect localhost
After a bit, I was able to connect and drive the device over adb:
$ ./adb devices
List of devices attached
localhost:5555 device
NOTE I'm not sure this is the whole story, as when testing this out for this answer, I deleted the dev-pc's adbkey and adbkey,pub and was still able to reconnect, so that seems a bit strange. It worked for me, but be aware, I'm not sure the mechanism.

In Android studio, Run menu > Run shows OFFLINE ... for the connected device.
Below is the procedure followed to solve it:
(Read the below note first) Delete the ~/.android/adbkey (or, rename to ~/.android/adbkey2, this is even better incase you want it back for some reason)
Note: I happened to do this step, but it didn't solve the problem, after doing all the below steps it worked, so unsure if this step is required.
Run locate platform-tools/adb
Note: use the path that comes from here in below commands
Kill adb server:
sudo ~/Android/Sdk/platform-tools/adb kill-server
You will get a Allow accept.. message popup on your device. Accept it. This is important, which solves the problem.
Start adb server:
sudo ~/Android/Sdk/platform-tools/adb start-server
In Android studio, do Run menu > Run again
It will show something like Samsung ... (your phone manufacture name).
Also installs the apk on device correctly this time without error.
Hope that helps.

Here is how I did it:
First you need to run the emulator on the host computer. I used Android Studio and I had to close it because I noticed that the adb process kept spawning.
Start port-forwarding using SSH in the development computer.
ssh -L 5554:localhost:5554 -L 5555:localhost:5555 user#emulator-host-ip
copy adbkey and adbkey.pub files found at: C:\Users\[your user]\.android from the host computer to the development computer. this step should get ride of the unauthorized problem
in the development computer kill the adb server and lookup connected devices:
$ ./adb kill-server
$ ./adb devices
List of devices attached
localhost:5555 device

React Native failed to compile giving Error on the Device

I'm new to the React Native application development. When I after creating project and configured my device, It gives error like below and stop responding.
BUILD SUCCESSFUL in 27s
26 actionable tasks: 1 executed, 25 up-to-date
'C:\Users\Amila' is not recognized as an internal or external command,
operable program or batch file.
info Starting the app (C:\Users\Amila Eranda\AppData\Local\Android
\Sdk/platform-tools/adb shell am start -n
com.awesomeproject/com.awesomeproject.MainActivity...
Starting: Intent { cmp=com.awesomeproject/.MainActivity }
It shows build is success but there is an error on the Device saying
Unable to load script. Make sure you're either running a metro server...
running the adb devices command shows there is a device connected to my PC. But it fails running it in the Device.

That error on your device means that your device cannot connect to the metro server running on your computer to get the js bundle. The app on your device is a temporary app used by react native to quickly download the javascript code from your computer and convert it to code your device can understand each and every time you make changes to your code. Your device must be connected to your computer either on the same wifi network (with metro bundler running in a terminal window on your computer) or through a usb cable (with usb debugging enabled on your device and adb reverse set on a command prompt on your computer).
Read this from the android documentation to find out how to enable developer options on your android device: https://developer.android.com/studio/debug/dev-options
If your android device lets you, you can create a hotspot and have your computer connect to it if you do not have wifi available and usb debugging does not work for you.
Read this from the react native documentation: https://facebook.github.io/react-native/docs/running-on-device#connecting-to-the-development-server-1

What is the ADB?

I keep reading tutorials where I'm supposed to enter something into the ADB command line and that it's in my Android sdk/platform-tools. So I find it, click on it, and a black screen comes up for about 2 seconds and while it's up, it scrolls through a bunch of text. So how am I supposed to use this "adb"?

It is called the Android Debug Bridge, and the Android Developers Site documentation does a better job of explaining it than I can:
http://developer.android.com/guide/developing/tools/adb.html
If you are looking for the adb command line, navigate to <sdk>/platform-tools/ and run
adb.exe shell
from the command line.

Pretty sure that is well documented since day 1 on the Android Debug Bridge
Android Debug Bridge (adb) is a versatile command line tool that lets
you communicate with an emulator instance or connected Android-powered
device. It is a client-server program that includes three components:
A client, which runs on your development machine. You can invoke a
client from a shell by issuing an adb command. Other Android tools
such as the ADT plugin and DDMS also create adb clients. A server,
which runs as a background process on your development machine. The
server manages communication between the client and the adb daemon
running on an emulator or device. A daemon, which runs as a background
process on each emulator or device instance.
So plain old English, ADB can be found on %ANDROID_HOME%/platform-toos/, and it's this magical command line that allows you to comunicate with your mobile device, either a physical or a Virtual device (AVD), so whenever you deploy you are passing the application through the device thanks to the ADB on a specific client port on your computer to the daemon port on the device.
Interesting things you can do with it?
Logcat: ./adb logcat allows you to see the log trace of each proces.
Install: ./adb install allows you to install apk to the device.
Killing:./adb kill-sever
Starting:./adb stat-server
Enter SQLite3: adb -s your_device shell
Use the monkey: adb shell monkey -v -p your.app.package 500 to
generate random events
And a lot more! Read the documentation it's beatiful and self-explanatory.