Android Studio error: cannot connect to daemon

user_8869649 0
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I've been using AS for months, but since two days I get an error when I try to run my app:

Unable to run 'adb': null
'C:\Users\lapof\AppData\Local\Android\Sdk\platform-tools\adb.exe start-server' failed -- run manually if necessary
* daemon not running; starting now at tcp:5037
could not read ok from ADB Server
* failed to start daemon
error: cannot connect to daemon

I've read about a lot of people having this problem, but the solutions provided don't work for me. I read these questions in particular:

A lot of answers to these questions say to close adb.exe from task manager, the problem is that adb.exe is not running and if I try to restart it by typing .\adb start-server on a PowerShell window I get the same error.

I also try to restart my PC but it didn't work. On the Android device I'm trying to connect to (Samsung Galaxy S8) I enabled USB debugging. I even tried to eliminate all the authorized devices, but nothing worked.

I checked if the 5037 port was used by other processes, but it is used by adb.exe (and the firewall state on that port is allowed and not limited). By the way, as I said, in the task manager adb.exe is not present.

Last I tried to follow the instructions provided in the last question I linked (basically I re-downloaded adb.exe). Initially I ran .\adb start-server and this strange error occurs:

* daemon not running. starting it now on port 5037 *
* daemon started successfully *
** daemon still not running
error: cannot connect to daemon

and then when I try to run my app on Android Studio it occurs this new error when it tries to start adb:

Unable to run 'adb': null
'C:\Users\lapof\AppData\Local\Android\Sdk\platform-tools\adb.exe start-server' failed -- run manually if necessary
ADB server didn't ACK
* failed to start daemon *

and then if I try to .\adb kill-server and then .\adb start-server or .\adb devices or .\adb usb the same error occurs again. Moreover when I connect my device now it asks me to authorize my PC to connect.

I don't know if this can help, but lately I deactivated a lot of Windows services (but I don't think I deactivated something related to Android Studio).

Details

  • PC: Compaq
  • PC OS: Windows 10 Home
  • Device: Samsung Galaxy S8 (Exynos)
  • Device OS: Android 8.0
  • AS version: 3.0.1
android-studio adb android
13 Answers

I had same problem a moment ago. I solved it:

Run CMD as Administrator

Enter adb devices to CMD.

The output for me is :

C:\WINDOWS\system32>adb devices
List of devices attached
* daemon not running; starting now at tcp:5037
* daemon started successfully
P9BCS87ABS9SCD5 device
user_57435300

The solution which worked for me -

Open Command Prompt as administrator and type

adb start-server

That's it

user_121188880

Usually that's caused by the WinNAT service, restarting which solves the issue.

Just open the Command Prompt as Administrator, and type the following commands there:

net stop winnat
net start winnat
user_59351120

I solved the problem on my own.

Out of frustration I opened Control Panel > System and security > Windows defender firewall > Allowed applications and I added adb.exe (both private and public networks).

I came back to Android Studio, ran the app and magically it managed to initialize ADB and my phone connected via USB was there.

I don't really know why this worked, since when I checked in Start > All Programs > Accessories > System Tools > Resource Monitor > Network > Listening Port it said that on port 5037 the firewall was allowed.

Moreover I don't know why up to a week ago all worked fine and now I had to do this process to make it work.

If someone more experienced manages to explain this behaviour better I'll update this answer (or accepts his as best answer)

user_88696490

Run CMD or PowerShell as administrator

Then run the following commands:

net stop winnat

In correct folder run:

adb start-server

net stop winnat
user_152148010

For my situation The latest platform is version 30.0.3. I also have the same problem as this:

* daemon not running. starting it now on port 5037 *
* daemon started successfully *

My solving:

user_135321360

Below solution solved my problem:

  1. Go to your task manager
  2. see if adb is running
  3. right click & end the task
  4. Go to command prompt
  5. run adb devices

it will work fine

user_164793640
  1. SDK Manager -> SDK tools
  2. Uncheck "Android SDK Platform - Tool"
  3. Click Apply
user_39913990

After using Android Studio and Emulator without any problems, suddenly it stop to connect to the Emulator, even adb server was running (killing and starting), firewalls raised for all the programs (adb.exe, qemu-system-x86_64.exe, studio64.exe, etc), port 5037 freed, uninstalled and installed again the programs, even the whole Android Studio from scratch. I got verything running OK, but no connection between AS and Emulator.

The solution to my problem was to run Android Studio AS ADMINISTRATOR, it seems that when I updated the program to 3.5.2 somehow the status changed, causing me the problem.

user_24504940

What worked for me in all adb unresolved cases:

adb kill-server

or

adb disconnect

I would just try them both and one will do the trick.

user_52006300

I had this issue several times. It seems if when system is starting, device is connected by USB cable, daemon will connect correctly and no problem will occur. Of course I want a better solution, because it is very hard for me to shut down and start again every time.

user_124788300

Had same issue after upgrading to Android Studio Bumblebee | 2021.1.1

To solve it, go to Settings -> Build, Excecution, Deployment -> Debugger

Then uncheck the option Enable adb mDNS for wierless debugger

user_16806370
user_175219690
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