Repository: flutter
Issue: From "flutter run" the app shows "In iOS 14+, debug mode Flutter apps can only be launched from Flutter tooling..." warning
Labels: c: regression,c: crash,platform-ios,engine,a: debugging,P2,team-ios,triaged-ios

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## Steps to Reproduce

Just run `flutter run --verbose`

**Expected results:** 

The app would start on my phone

**Actual results:** 

An error on the terminal and on the phone after it errors out I see a screen that says 
```
In iOS 14+, debug mode Flutter apps can only be launched from Flutter tooling, IDEs with Flutter plugins or from Xcode. Alternatively, build in profile or release modes to enable launching from the home screen
```

Interestingly enough, if I instead run `flutter build ios` and then hit play directly from Xcode, it works fine. But I can't debug my app with breakpoints doing that...

<details>
  <summary>Logs</summary>

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```
[ +611 ms] [100%] Installed package build/ios/iphoneos/Runner.app
[ +356 ms] ------ Debug phase ------
[        ] Starting debug of d167f1a8b5eed7cd0312f630a2da37135e6788f3 (D11AP, iPhone 7 Plus, iphoneos, arm64) a.k.a. 'iPhone de Jan Lubeck' connected through
USB...
[+1530 ms] [  0%] Looking up developer disk image
[  +14 ms] [ 95%] Developer disk image mounted successfully
[+1976 ms] [100%] Connecting to remote debug server
[        ] -------------------------
[  +29 ms] (lldb) command source -s 0 '/tmp/43EAB877-B245-4381-81F3-E5FF7A64EE92/fruitstrap-lldb-prep-cmds-d167f1a8b5eed7cd0312f630a2da37135e6788f3'
[        ] Executing commands in '/tmp/43EAB877-B245-4381-81F3-E5FF7A64EE92/fruitstrap-lldb-prep-cmds-d167f1a8b5eed7cd0312f630a2da37135e6788f3'.
[        ] (lldb)     platform select remote-ios --sysroot '/Users/jan/Library/Developer/Xcode/iOS DeviceSupport/14.0.1 (18A393)/Symbols'
[        ]   Platform: remote-ios
[        ]  Connected: no
[        ]   SDK Path: "/Users/jan/Library/Developer/Xcode/iOS DeviceSupport/14.0.1 (18A393)/Symbols"
[        ] (lldb)     target create "/Users/jan/Projects/flutter/safepass/source/build/ios/iphoneos/Runner.app"
[+1409 ms] Current executable set to '/Users/jan/Projects/flutter/safepass/source/build/ios/iphoneos/Runner.app' (arm64).
[        ] (lldb)     script fruitstrap_device_app="/private/var/containers/Bundle/Application/55D7041A-82BC-428F-8BD1-883183388AB4/Runner.app"
[        ] (lldb)     script fruitstrap_connect_url="connect://127.0.0.1:63737"
[        ] (lldb)     script fruitstrap_output_path=""
[        ] (lldb)     script fruitstrap_error_path=""
[        ] (lldb)     target modules search-paths add /usr "/Users/jan/Library/Developer/Xcode/iOS DeviceSupport/14.0.1 (18A393)/Symbols/usr" /System
"/Users/jan/Library/Developer/Xcode/iOS DeviceSupport/14.0.1 (18A393)/Symbols/System"
"/private/var/containers/Bundle/Application/55D7041A-82BC-428F-8BD1-883183388AB4" "/Users/jan/Projects/flutter/safepass/source/build/ios/iphoneos"
"/var/containers/Bundle/Application/55D7041A-82BC-428F-8BD1-883183388AB4" "/Users/jan/Projects/flutter/safepass/source/build/ios/iphoneos" /Developer
"/Users/jan/Library/Developer/Xcode/iOS DeviceSupport/14.0.1 (18A393)/Symbols/Developer"
[  +22 ms] (lldb)     command script import "/tmp/43EAB877-B245-4381-81F3-E5FF7A64EE92/fruitstrap_d167f1a8b5eed7cd0312f630a2da37135e6788f3.py"
[   +3 ms] (lldb)     command script add -f fruitstrap_d167f1a8b5eed7cd0312f630a2da37135e6788f3.connect_command connect
[        ] (lldb)     command script add -s asynchronous -f fruitstrap_d167f1a8b5eed7cd0312f630a2da37135e6788f3.run_command run
[        ] (lldb)     command script add -s asynchronous -f fruitstrap_d167f1a8b5eed7cd0312f630a2da37135e6788f3.autoexit_command autoexit
[        ] (lldb)     command script add -s asynchronous -f fruitstrap_d167f1a8b5eed7cd0312f630a2da37135e6788f3.safequit_command safequit
[        ] (lldb)     connect
[  +26 ms] (lldb)     run
[ +238 ms] success
[        ] Application launched on the device. Waiting for observatory port.
[   +9 ms] Attempting to forward device port 56985 to host port 63749
[        ] executing: /Users/jan/flutter/bin/cache/artifacts/usbmuxd/iproxy 63749:56985 --udid d167f1a8b5eed7cd0312f630a2da37135e6788f3
[+1008 ms] Forwarded port ForwardedPort HOST:63749 to DEVICE:56985
[  +11 ms] HttpException: Connection closed before full header was received, uri = http://localhost:63749/ws
[+2007 ms] HttpException: , uri = http://localhost:63749/ws
[+2004 ms] HttpException: , uri = http://localhost:63749/ws
[+2009 ms] HttpException: , uri = http://localhost:63749/ws
[+2003 ms] HttpException: , uri = http://localhost:63749/ws
[+2003 ms] Failed to connect directly, falling back to log scanning
[+5012 ms] Failed to connect with log scanning
[        ] Installing and launching... (completed in 37.9s)
[        ] Error launching application on iPhone de Jan Lubeck.
[   +4 ms] "flutter run" took 142,160ms.
[   +3 ms]
           #0      throwToolExit (package:flutter_tools/src/base/common.dart:14:3)
           #1      RunCommand.runCommand (package:flutter_tools/src/commands/run.dart:618:7)
           <asynchronous suspension>
           #2      FlutterCommand.verifyThenRunCommand (package:flutter_tools/src/runner/flutter_command.dart:1005:18)
           #3      _rootRunUnary (dart:async/zone.dart:1198:47)
           #4      _CustomZone.runUnary (dart:async/zone.dart:1100:19)
           #5      _FutureListener.handleValue (dart:async/future_impl.dart:143:18)
           #6      Future._propagateToListeners.handleValueCallback (dart:async/future_impl.dart:696:45)
           #7      Future._propagateToListeners (dart:async/future_impl.dart:725:32)
           #8      Future._completeWithValue (dart:async/future_impl.dart:529:5)
           #9      _AsyncAwaitCompleter.complete (dart:async-patch/async_patch.dart:40:15)
           #10     _completeOnAsyncReturn (dart:async-patch/async_patch.dart:311:13)
           #11     RunCommand.usageValues (package:flutter_tools/src/commands/run.dart)
           #12     _rootRunUnary (dart:async/zone.dart:1198:47)
           #13     _CustomZone.runUnary (dart:async/zone.dart:1100:19)
           #14     _FutureListener.handleValue (dart:async/future_impl.dart:143:18)
           #15     Future._propagateToListeners.handleValueCallback (dart:async/future_impl.dart:696:45)
           #16     Future._propagateToListeners (dart:async/future_impl.dart:725:32)
           #17     Future._completeWithValue (dart:async/future_impl.dart:529:5)
           #18     Future._asyncCompleteWithValue.<anonymous closure> (dart:async/future_impl.dart:567:7)
           #19     _rootRun (dart:async/zone.dart:1190:13)
           #20     _CustomZone.run (dart:async/zone.dart:1093:19)
           #21     _CustomZone.runGuarded (dart:async/zone.dart:997:7)
           #22     _CustomZone.bindCallbackGuarded.<anonymous closure> (dart:async/zone.dart:1037:23)
           #23     _microtaskLoop (dart:async/schedule_microtask.dart:41:21)
           #24     _startMicrotaskLoop (dart:async/schedule_microtask.dart:50:5)
           #25     _runPendingImmediateCallback (dart:isolate-patch/isolate_patch.dart:118:13)
           #26     _RawReceivePortImpl._handleMessage (dart:isolate-patch/isolate_patch.dart:169:5)


[ +161 ms] ensureAnalyticsSent: 160ms
[        ] Running shutdown hooks
[        ] Shutdown hook priority 4
[   +2 ms] Shutdown hooks complete
[        ] exiting with code 1
```

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     Run `flutter analyze` and attach any output of that command below.
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```
```

<!-- Finally, paste the output of running `flutter doctor -v` here. -->

```
[✓] Flutter (Channel dev, 1.23.0-18.0.pre, on Mac OS X 10.15.6 19G2021 x86_64, locale en-US)
    • Flutter version 1.23.0-18.0.pre at /Users/jan/flutter
    • Framework revision 37ebe3d82a (2 days ago), 2020-10-13 10:52:23 -0700
    • Engine revision 6634406889
    • Dart version 2.11.0 (build 2.11.0-213.0.dev)


[✓] Android toolchain - develop for Android devices (Android SDK version 29.0.3)
    • Android SDK at /Users/jan/Library/Android/sdk
    • Platform android-R, build-tools 29.0.3
    • 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-b3-6222593)
    • All Android licenses accepted.

[✓] Xcode - develop for iOS and macOS (Xcode 12.0.1)
    • Xcode at /Applications/Xcode.app/Contents/Developer
    • Xcode 12.0.1, Build version 12A7300
    • CocoaPods version 1.10.0.rc.1

[✓] Chrome - develop for the web
    • Chrome at /Applications/Google Chrome.app/Contents/MacOS/Google Chrome

[✓] Android Studio (version 4.0)
    • Android Studio at /Applications/Android Studio.app/Contents
    • Flutter plugin version 49.0.2
    • Dart plugin version 193.7547
    • Java version OpenJDK Runtime Environment (build 1.8.0_242-release-1644-b3-6222593)

[✓] VS Code (version 1.50.0)
    • VS Code at /Applications/Visual Studio Code.app/Contents
    • Flutter extension can be installed from:
      🔨 https://marketplace.visualstudio.com/items?itemName=Dart-Code.flutter

[✓] Connected device (5 available)
    • iPhone de Jan Lubeck (mobile) • d167f1a8b5eed7cd0312f630a2da37135e6788f3 • ios            • iOS 14.0.1
    • iPhone 11 Pro (mobile)        • 5D827B35-CC5F-4BD3-A451-5EB38B6ACF87     • ios            • com.apple.CoreSimulator.SimRuntime.iOS-13-5 (simulator)
    • macOS (desktop)               • macos                                    • darwin-x64     • Mac OS X 10.15.6 19G2021 x86_64
    • Web Server (web)              • web-server                               • web-javascript • Flutter Tools
    • Chrome (web)                  • chrome                                   • web-javascript • Google Chrome 86.0.4240.80
    ! Error: iPhone de Jan Lubeck is busy: Copying cache files from device. Xcode will continue when iPhone de Jan Lubeck is finished. (code -10)

• No issues found!
```

</details>