main isolate is paused in the debugger

[matthewchung74]

I get this error when flutter web

not that it matters, but have tried using vscode

        {
            "name": "Flutter",
            "request": "launch",
            "type": "dart",
            "args": ["-d", "chrome","--web-port", "9000", "--web-enable-expression-evaluation"],
        }

and command line too

flutter run  -d chrome --web-port 9000

flutter doctor -v
[✓] Flutter (Channel stable, 2.0.4, on Mac OS X 10.15.7 19H114 darwin-x64, locale en-US)
    • Flutter version 2.0.4 at /Users/mattc/flutter
    • Framework revision b1395592de (5 days ago), 2021-04-01 14:25:01 -0700
    • Engine revision 2dce47073a
    • Dart version 2.12.2

[✓] Android toolchain - develop for Android devices (Android SDK version 30.0.3)
    • Android SDK at /Users/mattc/Library/Android/sdk
    • Platform android-30, build-tools 30.0.3
    • Java binary at: /Applications/Android Studio.app/Contents/jre/jdk/Contents/Home/bin/java
    • Java version OpenJDK Runtime Environment (build 1.8.0_242-release-1644-b3-6915495)
    • All Android licenses accepted.

[✓] Xcode - develop for iOS and macOS
    • Xcode at /Applications/Xcode.app/Contents/Developer
    • Xcode 12.4, Build version 12D4e
    • CocoaPods version 1.10.1

[✓] Chrome - develop for the web
    • Chrome at /Applications/Google Chrome.app/Contents/MacOS/Google Chrome

[✓] Android Studio (version 4.1)
    • Android Studio at /Applications/Android Studio.app/Contents
    • Flutter plugin can be installed from:
      🔨 https://plugins.jetbrains.com/plugin/9212-flutter
    • Dart plugin can be installed from:
      🔨 https://plugins.jetbrains.com/plugin/6351-dart
    • Java version OpenJDK Runtime Environment (build 1.8.0_242-release-1644-b3-6915495)

[✓] VS Code (version 1.55.0)
    • VS Code at /Applications/Visual Studio Code.app/Contents
    • Flutter extension version 3.21.0

[✓] Connected device (2 available)
    • iPhone 12 Pro Max (mobile) • 28DA59A2-DEEB-4FD9-AC8B-86A0024DFC74 • ios            •
      com.apple.CoreSimulator.SimRuntime.iOS-14-4 (simulator)
    • Chrome (web)               • chrome                               • web-javascript • Google Chrome
      89.0.4389.114

• No issues found!

[kenzieschmoll]

That is a floating toolbar intended to notify you when your app is paused at a breakpoint. Some parts of DevTools will not work when your app is paused. If you click the green resume button, your app should resume and DevTools should work as intended.

[matthewchung74]

@kenzieschmoll thanks for replying. I have tried that many times, and it inconsistently works. now sure how to get more diagnostics on the problem.

[kenzieschmoll]

do you have a breakpoint that keeps getting hit? Can you switch to the debugger tab to resume?

[matthewchung74]

I've been trying to get a video of it happening, but of course, it is working now. While I had breakpoints set in vscode, none of them were hit. When I pressed the green button on the floating toolbar, nothing happened.

[matthewchung74]

@kenzieschmoll i do have a video capturing it, but am not sure if it will be helpful at all. there are no breakpoints which are pausing execution and I do hit the green go button a couple times.

Screen.Recording.2021-04-06.at.5.25.19.PM.mov

[kenzieschmoll]

It's hard to tell from the video, but has your app completely finished launching from VS code?
cc @DanTup

[DanTup]

The Chrome window shows an "Awww, snap!" error, which may be related. Do you have part files in this project? There's an issue being looked at at dart-lang/webdev#1271 related to that causing problems.

[annagrin]

@DanTup thanks for referencing! I do suspect it is related to one of two problems that are going to be fixed in dart-lang/webdev#1296:

• failing to set breakpoints in part files
• data race if more than one breakpoint was set in the same file, with more breakpoints making it more likely to happen.

@matthewchung74 do you see the same issue if there is only one breakpoint in your app, in main (and no breakpoint in any part files)?

[matthewchung74]

@DanTup not deliberately using any part files. i am importing a number of firebase libraries and riverpod, might be used in there? I uploaded the repo : https://github.com/matthewchung74/flutter_debug . it's just the start of a flutter web project using firebase email magic link.

@annagrin it's not happening right now, but once it does, I'll try to reproduce with 1 breakpoint in main. I did notice last night when I shut down on my mac, there were a couple chrome processes that were unresponsive and difficult to kill.

[matthewchung74]

It happened to me a couple of times over the week, although I haven't been able to isolate it. Each time, I had a lot of breakpoints set. I did notice if I removed all my breakpoints, the issue went away.

[matthewchung74]

i can close this for now, and if I find a way to reproduce, will reopen.