396

When I run my flutter application it show

Waiting for another flutter command to release the startup lock

this messages and not proceed further.

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2
  • In My case , i open two diff project and I run the two commands on both 1) flutter build apk 2) flutter run. it stopped executing the other project and waited for the finishing of first project, as first projected finished its execution , second project started execution.
    – M.ArslanKhan
    Dec 6, 2019 at 20:33
  • Below answers not needed. Just setup your sdk path in android studio. Close project, open project. Select pubspec.yaml run (Pub upgrade, Pub get, flutter doctor).
    – Amit Khetan
    May 25, 2021 at 10:39

25 Answers 25

Reset to default
866

In my case, the following command in Terminal helped (as suggested by Günter Zöchbauer's comment):

killall -9 dart

On Windows, run the following in a Command Prompt or PowerShell window (as suggested by upupming's comment):

taskkill /F /IM dart.exe

(You can read about taskkill flags in Windows here)

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2
  • then,how to proceed,im new to flutter, i just cloned the flutter git and set the env var?
    – Aashiq
    Jun 13, 2020 at 5:34
  • I would suggest -9 as a last resort; attempting without it first would be preferred.
    – miken32
    Jul 20, 2022 at 17:55
95

Remove this file:

<YOUR FLUTTER FOLDER>/bin/cache/lockfile

This releases the occupied lock and makes you able to run other commands.

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3
  • 1
    But the lockfile is locked. It is in use and I can't seem to delete it. OK, it works, but you need to close Android Studio and wait about a minute as well....then you can delete that file.
    – Yster
    Oct 2, 2019 at 19:43
  • This answer is good if actually no application is using flutter i.e android studio, vscode, cmd, ... etc
    – Eslam Sameh Ahmed
    Jun 21, 2021 at 14:24
  • it doesn't work. I delete it and run the command again same problem shows up. I am using ubuntu, never had this much issue in windows
    – rebel_codeaz
    Dec 24, 2022 at 14:18
29

You can try to kill all flutter processes.

TL;DR - go to point 4)

1) List of the processes:

ps aux

2) Search name containing with flutter:

ps aux | grep flutter

where output can be like there:

stackoverflow     16697   1.5  0.0  4288316    704   ??  S    10:02PM   0:15.80 bash /flutter_path/flutter/bin/flutter --no-color build apk
stackoverflow      2800   1.5  0.0  4288316    704   ??  S     9:59PM   0:18.49 bash /flutter_path/flutter/bin/flutter --no-color pub get
stackoverflow      1215   1.5  0.0  4280124    700   ??  S     9:58PM   0:18.89 bash /flutter_path/flutter/bin/flutter --no-color config --machine
stackoverflow      8449   1.5  0.0  4296508    716   ??  S    10:00PM   0:17.20 bash /flutter_path/flutter/bin/flutter --no-color pub get
stackoverflow      1326   1.4  0.0  4288316    708   ??  S     9:58PM   0:18.97 bash /flutter_path/flutter/bin/flutter daemon
stackoverflow     16687   0.0  0.0  4279100    820   ??  S    10:02PM   0:00.01 bash /flutter_path/flutter/bin/flutter --no-color build apk
stackoverflow      8431   0.0  0.0  4288316    804   ??  S    10:00PM   0:00.02 bash /flutter_path/flutter/bin/flutter --no-color pub get
stackoverflow      2784   0.0  0.0  4288316    704   ??  S     9:59PM   0:00.01 bash /flutter_path/flutter/bin/flutter --no-color pub get
stackoverflow      1305   0.0  0.0  4280124    712   ??  S     9:58PM   0:00.01 bash /flutter_path/flutter/bin/flutter daemon
stackoverflow      1205   0.0  0.0  4279100    788   ??  S     9:58PM   0:00.01 bash /flutter_path/flutter/bin/flutter --no-color config --machine
stackoverflow     11416   0.0  0.0  4268176    536 s000  R+   10:18PM   0:00.00 grep --color flutter

3) Get processes ID

We need content from second column (from above output):

ps aux | grep flutter | awk '{print $2}'

4 a) Kill "automatically":

To list, search and kill all of them you can use

kill $(ps aux | grep flutter | grep -v grep  | awk '{print $2}')

(you can run it also with sudo)

or

ps aux | grep flutter | grep -v grep | awk '{print $2}' | xargs kill -15

4 b) Kill manually

You can kill processes one-by-one using:

sudo kill -15 <process_ID>

e.g. to kill process with id 13245 use:

sudo kill -15 13245

If -15 will not work, you can try -2 or -1.

Final option it is -9 which should not be used because it prevents the process from doing any cleanup work.

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0
24

I use a Mac with Visual Studio Code and this is what worked:

Shutdown your PC and switch it on again. Don't use the restart function. I restarted 2 times and it didn't work. Only shutdown worked.

PS: I tried out the following:

  1. Delete lockfile;
  2. Run killall -9 dart;
  3. Restart my PC.

But they all didn't work.

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0
23

In Windows :

Press: Ctrl + Alt + Delete

  • In task manager find out your editor such as VS Studio or Android Studio
  • In that Find "dart" and End that Task
  • Then close your editor
  • Open editor again
  • let editor to complete all things, after that run your query that will work
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1
  • For me there's no dart task.
    – Yster
    Oct 2, 2019 at 19:44
15

Most are saying killall -9 dart but nobody mentioned pkill -f dart which worked for me.

The difference between the 2 is explained here.

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1
  • 1
    pkill -f dart worked for me on MacOs Ventura.
    – Pedro Massango
    Feb 14, 2023 at 23:01
9

Exit from your IDE, then from start manager stop all dart related files(if any have).
Then go to
"FLUTTER DIRECTORY"/bin/cache/lockfile
and delete this lockfile

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7

I have the same issue, I tried all the above solutions, but none of them worked for me. Then I searched the keywords in flutter directory, and found the following code. So I tried to delete bin/cache/.upgrade_lock, and it worked finally.

enter image description here

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5

This also happens when you have opened the flutter project in the Editor. Close the Editor and re-run the command

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2
  • To add up to this, I am using vs code and I have to close all instances of vs code (e.g. api & flutter projects). Then I am able to re-run flutter run.
    – josevoid
    Feb 21, 2022 at 7:24
  • NOT WORKED DEAR :)
    – Kamlesh
    Aug 27, 2023 at 9:58
5

I have tried all of below steps, but none worked.

  1. Delete lockfile;
  2. Run killall -9 dart;
  3. Restart my PC.

Below is the final command that worked for me

rm -rf <flutter_dir>bin/cache/.upgrade_lock
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4

I tried all previous suggestions but without benefit. Finally when I connect my pc to internet and wait flutter to release then 5 minutes solved

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4

In VS code run 

flutter clean

in the terminal. This fixed my issue.

code image

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2
  1. Delete pubspec.lock file
  2. Run "flutter pub get" from terminal or editor shortcut ("get packages" AndroidStudio or this logo Visual Studio) in pubspec.yaml file.
  3. Wait for download.
  4. If it doesn't work relaunch your editor then repeat step 2..
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2

For me, the issue's root cause on my Mac device was a version of the flock binary it was not expecting. Removing it from the path did the trick; probably a BSD vs GNU syntax issue.

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1
  • I had the same cause. brew upgrade flock - helped me
    – Denis L
    Oct 29, 2020 at 19:14
2

I tried all the previous suggestions but no one solved the problem.. I did the following and it works (Windows 11):

  1. run command: taskkill /F /IM dart.exe in TERMINAL in VS code.
  2. close VS code.
  3. delete lockfile in <flutter_SDK_bath>\bin\cache.
  4. restart computer.
  5. run command: flutter doctor in Power Shell. (especially after updating flutter SDk).
  6. run command flutter pub get in application path.

that's works for me..

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1

  1. Turn off Android Studio.

  2. Open flutter installation directory /bin/cache.

  3. Delete lockfile.

  4. At this point, you can execute the flutter related command on the command line to solve the problem perfectly.

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1

You can remove flutter and "install again", so fastest way is to:

1) Check where you have flutter (as executable)

To check it, you can run:

which flutter

And you can expect such output:

/your_user/your_path/flutter/bin/flutter

2) Go to this directory

Above path is directly to flutter, but we would like to go to directory so "one earlier" in path:

cd /your_user/your_path/flutter/bin

3) Check is it git repository

It should be, but it's worth to check.

Run one of the git command e.g.

git status

or

git branch

When it's git repository you will receive some info about it or correct list of branches.

4) Remove all of the files

rm -R *

5) "revert" removal to have only necessary files:

git co -- .

6) Voila!

You can run just flutter version and commands should work (and Flutter will fetch some necessary data).

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1

Restart your computer or simple logout from the current user and login again.

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3
  • 2
    Please convince me logging out&in solves the problem. (And, if platform dependent or tried on one, only, mention the platform.)
    – greybeard
    Apr 16, 2020 at 9:38
  • 1
    using Mac OS Mojave
    – Mithilesh Parmar
    Apr 16, 2020 at 9:51
  • 2
    I faced similar issues and the above method solved my problem
    – Mithilesh Parmar
    Apr 16, 2020 at 9:51
0

If you are using Windows, you can open the task manager and under the 'Processes' tab search for processes named 'dart'. End all those tasks.

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0

In Android Studio, It's Work for me

Stop your app if it still runs on the phone or disconnect the your testing device.

Then try to install the package again.

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0

There are some action to do:

1- in pubspec.yaml press "packages get" or in terminal type " flutter packages get" and wait seconds.

if this doesn't work :

2-type flutter clean then do step(1)

if this doesn't work too :

3-type killtask /f /im dart.exe

if this doesn't work too :

4- close android studio and then restart your pc.

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0

Nothing of ALL these answers didn't helped me.

The only one solution was to remove whole flutter stuff (and reinstall flutter from git):

<flutter directory>
<user>/.flutter_tool_state
<user>/.dart
<user>/.pub-cache
<user>/.dartServer
<user>/.flutter
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0

i had same issue , in terminal executed this command

taskkill /F /IM dart.exe

and Flutter Clean , Flutter pub get then restarted the pc and it worked.

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0
  • In the terminal type flutter packages get
  • Type flutter clean

If it doesn't work do this:

  • Type killtask /f /im dart.exe.

Close Android Studio and then restart your PC.

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0

I tried most of the answers here, but what I believe is happening is that there is some hidden dart process running when you open any app like VSCode or Android Studio. My steps were a lot simpler to solve this:

  • Shut off your computer (don't just restart it) and turn it back on
  • Don't open VSCode or Android Studio
  • If there's any dart process running, kill it with task manager or with the commands provided by the folks here
  • Go to {FlutterDirectory}/bin/cache and delete everything there (it's just cache so doesn't matter)
  • Open terminal
  • Run flutter clean

I believe the flutter/dart extension for VSCode might lock it if you try to run flutter clean in VSCode, but you can try it

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