Error in Flutter myapp

[bhardayash486]

TypeError: Instance of '_JsonMap': type '_JsonMap' is not a subtype of type 'List<Object?>'

at Rti._generalAsCheckImplementation [as _as] (http://localhost:55963/dwds/src/injected/client.js:2729:79)
at Rti._installSpecializedAsCheck (http://localhost:55963/dwds/src/injected/client.js:2664:22)
at BuiltJsonSerializers._deserialize$3 (http://localhost:55963/dwds/src/injected/client.js:20953:36)
at BuiltJsonSerializers.deserialize$2$specifiedType (http://localhost:55963/dwds/src/injected/client.js:20938:21)
at BuiltJsonSerializers.deserialize$1 (http://localhost:55963/dwds/src/injected/client.js:20946:19)
at Object._deserializeEvent (http://localhost:55963/dwds/src/injected/client.js:9920:35)
at http://localhost:55963/dwds/src/injected/client.js:26905:26
at _wrapJsFunctionForAsync_closure.$protected (http://localhost:55963/dwds/src/injected/client.js:3893:15)
at _wrapJsFunctionForAsync_closure.call$2 (http://localhost:55963/dwds/src/injected/client.js:13631:12)
at Object._asyncStartSync (http://localhost:55963/dwds/src/injected/client.js:3857:20)
at main__closure8.$call$body$main__closure (http://localhost:55963/dwds/src/injected/client.js:27054:16)
at main__closure8.call$1 (http://localhost:55963/dwds/src/injected/client.js:26892:19)
at StaticClosure._rootRunUnary (http://localhost:55963/dwds/src/injected/client.js:4391:18)
at _CustomZone.runUnary$2$2 (http://localhost:55963/dwds/src/injected/client.js:15254:39)
at _CustomZone.runUnaryGuarded$1$2 (http://localhost:55963/dwds/src/injected/client.js:15201:14)
at _ForwardingStreamSubscription._sendData$1 (http://localhost:55963/dwds/src/injected/client.js:14739:19)
at _ForwardingStreamSubscription._add$1 (http://localhost:55963/dwds/src/injected/client.js:14684:15)
at _ForwardingStreamSubscription._add$1 (http://localhost:55963/dwds/src/injected/client.js:15080:12)
at _MapStream._handleData$2 (http://localhost:55963/dwds/src/injected/client.js:15140:12)
at _ForwardingStreamSubscription._handleData$1 (http://localhost:55963/dwds/src/injected/client.js:15106:20)
at tear_off.<anonymous> (http://localhost:55963/dwds/src/injected/client.js:1637:45)
at StaticClosure._rootRunUnary (http://localhost:55963/dwds/src/injected/client.js:4391:18)
at _CustomZone.runUnary$2$2 (http://localhost:55963/dwds/src/injected/client.js:15254:39)
at _CustomZone.runUnaryGuarded$1$2 (http://localhost:55963/dwds/src/injected/client.js:15201:14)
at CastStreamSubscription.__internal$_onData$1 (http://localhost:55963/dwds/src/injected/client.js:11639:30)
at tear_off.<anonymous> (http://localhost:55963/dwds/src/injected/client.js:1637:45)
at StaticClosure._rootRunUnary (http://localhost:55963/dwds/src/injected/client.js:4391:18)
at _CustomZone.runUnary$2$2 (http://localhost:55963/dwds/src/injected/client.js:15254:39)
at _CustomZone.runUnaryGuarded$1$2 (http://localhost:55963/dwds/src/injected/client.js:15201:14)
at _ControllerSubscription._sendData$1 (http://localhost:55963/dwds/src/injected/client.js:14739:19)
at _DelayedData.perform$1 (http://localhost:55963/dwds/src/injected/client.js:14914:59)
at _PendingEvents_schedule_closure.call$0 (http://localhost:55963/dwds/src/injected/client.js:14973:14)
at StaticClosure._rootRun (http://localhost:55963/dwds/src/injected/client.js:4372:18)
at _CustomZone.run$1$1 (http://localhost:55963/dwds/src/injected/client.js:15246:39)
at _CustomZone.runGuarded$1 (http://localhost:55963/dwds/src/injected/client.js:15189:14)
at _CustomZone_bindCallbackGuarded_closure.call$0 (http://localhost:55963/dwds/src/injected/client.js:15378:25)
at StaticClosure._rootRun (http://localhost:55963/dwds/src/injected/client.js:4376:16)
at _CustomZone.run$1$1 (http://localhost:55963/dwds/src/injected/client.js:15246:39)
at _CustomZone.runGuarded$1 (http://localhost:55963/dwds/src/injected/client.js:15189:14)
at _CustomZone_bindCallbackGuarded_closure.call$0 (http://localhost:55963/dwds/src/injected/client.js:15378:25)
at Object._microtaskLoop (http://localhost:55963/dwds/src/injected/client.js:4220:24)
at StaticClosure._startMicrotaskLoop (http://localhost:55963/dwds/src/injected/client.js:4226:11)
at _AsyncRun__initializeScheduleImmediate_internalCallback.call$1 (http://localhost:55963/dwds/src/injected/client.js:13509:9)

[nshahan]

@bhardayash486
Do you have any reproduction steps that lead you to this crash? I'm not able to reproduce this.

What version of flutter are you running, what actions did you take that cause this?

[bhardayash486]

Flutter 3.44.7 • channel stable • https://github.com/flutter/flutter.git Framework • revision 84fc5cbb22 (7 days ago) • 2026-07-17 10:20:17 -0700 Engine • hash 7076f47b1d1a3a0edfd8837b17dc15be6abab661 (revision 69c8c61792) (8 days ago) • 2026-07-15 20:46:58.000Z Tools • Dart 3.12.2 • DevTools 2.57.0 This Version I Use as a college student

…

On Fri, Jul 24, 2026 at 5:39 AM Nicholas Shahan ***@***.***> wrote: *nshahan* left a comment (dart-lang/webdev#2849) <#2849 (comment)> @bhardayash486 <https://github.com/bhardayash486> Do you have any reproduction steps that lead you to this crash? I'm not able to reproduce this. What version of flutter are you running, what actions did you take that cause this? — Reply to this email directly, view it on GitHub <#2849?email_source=notifications&email_token=CGRHWY2EYQQCV2GDG7HJPWD5GKSJ3A5CNFSNUABFM5UWIORPF5TWS5BNNB2WEL2JONZXKZKDN5WW2ZLOOQXTKMBWGQ3TMMJWHAZKM4TFMFZW63VHNVSW45DJN5XKKZLWMVXHJLDGN5XXIZLSL5RWY2LDNM#issuecomment-5064761682>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/CGRHWY73IEVGCA3CBATWUID5GKSJ3AVCNFSNUABFKJSXA33TNF2G64TZHMYTCNBZGI2TMOJQHNEXG43VMU5TIOJUHEYTQNBTGYZKC5QC> . Triage notifications, keep track of coding agent tasks and review pull requests on the go with GitHub Mobile for iOS <https://github.com/notifications/mobile/ios/CGRHWYZHFSW237YC6AOQ3GD5GKSJ3A5CNFSNUABFM5UWIORPF5TWS5BNNB2WEL2JONZXKZKDN5WW2ZLOOQXTKMBWGQ3TMMJWHAZKM4TFMFZW63VHNVSW45DJN5XKKZLWMVXHJKTGN5XXIZLSL5UW64Y> and Android <https://github.com/notifications/mobile/android/CGRHWY66W6PCCZZ2RQIANLT5GKSJ3A5CNFSNUABFM5UWIORPF5TWS5BNNB2WEL2JONZXKZKDN5WW2ZLOOQXTKMBWGQ3TMMJWHAZKM4TFMFZW63VHNVSW45DJN5XKKZLWMVXHJLTGN5XXIZLSL5QW4ZDSN5UWI>. Download it today! You are receiving this because you were mentioned.Message ID: ***@***.***>

[nshahan]

The stack trace you posted looks like it contains references to an older version. I suspect that you are getting an old version of the dwds injected client somehow. If you are still having the problem, when you run the app open the browsers developer tools and open the client.js file in the sources panel. Copy the comment from the top of the file that contains information about how it was compiled and share it here. It should contain the version of the Dart SDK that was used to compile it. This can help us pinpoint if you are running an older version.