AnimationController The named parameter 'vsync' isn't defined

Question

AnimationController stopped working because somehow vsync is not a named parameter anymore.

This line of code stopped working.

controller = AnimationController(duration: Duration(seconds: 3), vsync: this);

It now shows an error saying:

The named parameter 'vsync' isn't defined.
Try correcting the name to an existing named parameter's name, or defining a named parameter with the name 'vsync'.dartundefined_named_parameter

I use this exact same code in two different apps, in one of them I just removed the fading text animation as a hot fix, but on the other app I need a real fix. Has anyone seen this problem recently?

Note:

-This exact same code has been working for months and stopped working after an update.

-The surrounding class does have: with TickerProviderStateMixin

class FadingText extends StatefulWidget {
  final String text;
  final int seconds;
  final TextStyle style;

  FadingText({this.text, this.seconds, this.style});

  @override
  _FadingTextState createState() => _FadingTextState();
}

class _FadingTextState extends State<FadingText> with TickerProviderStateMixin {
  AnimationController controller;
  Animation animation;

  @override
  Widget build(BuildContext context) {
    return Container(
      child: FadeTransition(
        opacity: animation,
        child: Text(widget.text, style: widget.style,),
      ),
    );
  }

  @override
  void initState() {
    super.initState();

    controller = AnimationController(duration: Duration(seconds: widget.seconds), vsync: this);
    animation = Tween(begin: 0.5, end: 1.0).animate(controller);

    animation.addStatusListener((status) {
      if (status == AnimationStatus.completed) { controller.reverse(); }
      else if (status == AnimationStatus.dismissed) { controller.forward(); }
    });

    controller.forward();
  }


  @override
  void dispose() {
    controller.dispose();
    super.dispose();
  }

}

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Could you post your class constructor? And where you tried to implement your Controller? — Mariano Zorrilla, Aug 01 '20 at 16:53
could you also post your "flutter doctor -v"? Is the same issue happening using the single ticker provider? — Mariano Zorrilla, Aug 01 '20 at 17:09
I added the results of flutter doctor -v... also checked that the class is not duplicated. — Chamanhm, Aug 01 '20 at 19:35
I am currently running into the same issue. This is probably a bug introduce since the last update... Try to open an issue on the [flutter GitHub](https://github.com/flutter/flutter/issues) page it should be fixed quickly if this issue is as spread as I think. By checking here : https://github.com/flutter/flutter/commit/a7e868dd876f4b84462cc29fa2dd4092280a1d7a#diff-82a88b0b4aa73ca8c85c9fc068be95b6 You can see the modifications made 4 days ago. — Quentin Aoustin, Aug 02 '20 at 14:36

score 126 · Accepted Answer · edited Nov 29 '21 at 23:14

126

In your pubspec.yml

change this to:

environment:
  sdk: ">=2.8.0 <3.0.0"

and flutter pub get

in Android Studio invalidate the cache and restart, you should be good to go.

Credit : https://github.com/flutter/flutter/issues/62752#issuecomment-667744745

edited Nov 29 '21 at 23:14

MendelG

14,885
4
25
52

answered Aug 03 '20 at 12:32

Quentin Aoustin

1,403
1
7
6

19

to "invalidate the cache and restart" in android studio click (File -> Invalidate Caches/Restart) – sultanmyrza Aug 05 '20 at 07:26
4

As for me I need one more step is reload IDE :D Thanks, it works like a charm. – Quyen Anh Nguyen Aug 21 '20 at 03:51
3

for VSCode, do 'Restart Analysis Server', ctrl+shift+p to bring up the command palette and type 'analysis' to search for it. This will save you from restarting the IDE – Nouman Hanif Mar 08 '21 at 23:32

score 35 · Answer 2 · answered Aug 18 '20 at 00:54

35

What happened is that @required syntax was migrated during the rollout of null-safety to now just be required. This is valid new-Dart, but if you upgrade with your editor open, it will have stale build rules. Simply run flutter clean and restart your IDE, and that should do it.

Hopefully no need to restart your computer, change internet providers, etc.

answered Aug 18 '20 at 00:54

Craig Labenz

2,489
3
22
17

1

Editor Restart fixed it – Hashem Aboonajmi Jun 20 '21 at 04:26

Shad · Answer 3 · 2021-07-14T16:16:59.127

23

A few things (unfortunately not pinpointed) that help me with issues like this:

**edit: I would recommend doing these in order, hopefully the issue will be solved before you reach the end of the list.

run flutter upgrade
run flutter pub get
run flutter clean
restart IDE
change flutter channel
and in this case, change minimum SDK version from 2.7.0 to 2.8.0.

There are, of course, caveats to a few of these tactics. More experienced developers would surely have more details to offer, but I haven't encountered issues with this approach.

edited Jul 14 '21 at 16:16

answered Aug 08 '20 at 17:20

Shad

400
3
7

Only doing the first four steps solved the issue. – Dec 21 '20 at 02:44

score 19 · Answer 4 · answered Aug 03 '20 at 09:58

19

Had the same issue after upgrading flutter. Restarting the IDE fixed the problem.

answered Aug 03 '20 at 09:58

Stefan Ciobotaru

2,398
1
12
5

score 13 · Answer 5 · answered Oct 15 '20 at 10:12

13

I ran into the same issue when I upgraded to Flutter 1.22.

I am using VS Code.

Simply run: Flutter Clean in the Terminal and restart your IDE. That should fix the problem!

answered Oct 15 '20 at 10:12

iMujtaba8488

241
3
9

score 7 · Answer 6 · answered Jan 04 '21 at 11:49

7

if you still getting same error with vsync: this you probably don't have with TickerProviderStateMixin in your State definition

correct your state definition like this

class _BookListState extends State<BookList> with TickerProviderStateMixin {
  final BookHelper _bookHelper = BookHelper.instance;
}

answered Jan 04 '21 at 11:49

FarukT

1,560
11
25

This solved the issue for me, thank – Jan Oct 06 '21 at 13:30

GAURAV JOSHI · Answer 7 · 2021-02-06T16:02:47.967

I have given 5 steps and apply all the steps in the same order as mentioned and I think your problem will be solved.

Step 1: Change the SDK version in the pubspec.yaml to 2.8

environment:
sdk: '>=2.8.0 <3.0.0'

Step 2: Open terminal and run

flutter upgrade

Step 3: After Step 2, get all the package by running this command

flutter pub get

Step 4: Then use this command to clean flutter

flutter clean

Step 5: Close the IDE (like VS Code, Android Studio) and then reopen it. That's all!!!

vsync will appear back again.

Apart from vsync, the colors property in LinearGradient was also missing and after I applied all these steps, colors property along with vsync reappeared.

score 4 · Answer 8 · answered Aug 07 '20 at 10:12

4

After upgrading flutter.

Restarting the IDE
If necessary, reboot your computer

answered Aug 07 '20 at 10:12

Adonias Vasquez

1,014
13
11

canerkaseler · Answer 9 · 2021-09-23T14:16:39.997

How did I solve it in Android Studio ?

Firstly, previous answers can be wrong because I did not change my SDK range:

environment:
  sdk: ">=2.1.0<3.0.0"

I wrote code (vsync) in my dart file and I know Android Studio shows error but do not care, just write your code:

AnimationController _animationController = AnimationController(
  duration: Duration(seconds: 3),
  vsync: this,
);

After that, close your project and then open it again. System can understand by itself. That's all ! You can see my screen shot proof:

score 2 · Answer 10 · answered Mar 05 '21 at 02:42

2

how about add this,

class _AnimationScreenState extends State ///

with SingleTickerProviderStateMixin {

/// }

answered Mar 05 '21 at 02:42

seungyongC

41
4

This is not the answer to the question, but it did help me ! Without it, you cannot use `this` for the parameter `vsync` – Jack' Nov 14 '22 at 16:15

subhajit das · Answer 11 · 2020-10-03T19:44:35.720

1

Just restarting the IDE solves this issue for me

and don't forget to inheritate Tickerprovider.

edited Oct 03 '20 at 19:44

answered Sep 26 '20 at 19:16

subhajit das

383
3
8

I first change `sdk: ">=2.8.0 <3.0.0"` in `pubspec.ym`l and then a restart, not sure which one solved the issue. – Elia Weiss Oct 05 '20 at 07:35

score 1 · Answer 12 · answered Nov 03 '20 at 12:59

1

I was having same issue, I upgraded the SDK and then did Invalidate caches and Restart and It worked for me.

answered Nov 03 '20 at 12:59

Yogesh Tanwar

27
7

Muhammad Tameem Rafay · Answer 13 · 2021-09-15T20:35:53.287

1

Don't do anything just invalid the cache and restart your IDE

flutter clean
restart your IDE

edited Sep 15 '21 at 20:35

answered Jun 03 '21 at 16:53

Muhammad Tameem Rafay

3,602
2
21
32

score 1 · Answer 14 · answered Jul 14 '21 at 17:05

1

You have to place that line inside initState() method, as follow:

@override
void initState() {
super.initState();
_controller = AnimationController(duration: expandDuration, vsync: this);
}

answered Jul 14 '21 at 17:05

Kalpesh Khandla

758
1
9
22

score 0 · Answer 15 · answered Feb 15 '21 at 09:34

0

in my case, I resolved the issue after setting the dart and flutter SDK path in android studio.

answered Feb 15 '21 at 09:34

Muhammad Kashif

253
3
6

score 0 · Answer 16 · answered Apr 15 '21 at 10:26

0

This worked for me

Change the SDK version in the pubspec.yaml to '>=2.8.0 <3.0.0'

Then Run following commands :

flutter upgrade
flutter pub get
flutter clean

And Restart IDE

answered Apr 15 '21 at 10:26

GAURAV MOKASHI

1,906
2
14
17

score 0 · Answer 17 · answered Jan 06 '23 at 03:38

0

Replacing

with TickerProviderStateMixin

with

with SingleTickerProviderStateMixin

worked for me.

answered Jan 06 '23 at 03:38

Alexander Barragán

1
1

AnimationController The named parameter 'vsync' isn't defined

17 Answers17