[tool_crash] RpcException trying to start a widget preview using a DTD connection that already has a widget preview #179883
Description
I tried to start a widget preview using the DTD URI for my VS Code instance. It failed with the error below (which I presume is because the widget preview inside VS Code was already connected to this instance of DTD).
I think it should either work, or it prints a friendly message explaining that there is already a widget preview connecting to this instance of DTD.
C:\Users\danny\AppData\Local\Temp\flutter_tools.c4b78f7a\widget_preview_scaffoldd2781a7f\preview_manifest.json
Finding previews in D:\Dev\Test Projects\flutter_counter...
Found 4 previews.
Oops; flutter has exited unexpectedly: "JSON-RPC error 111: Service already registered".
A crash report has been written to C:\Users\danny\AppData\Local\Temp\flutter_tools.c4b78f7a\widget_preview_scaffoldd2781a7f\flutter_01.log
This crash may already be reported. Check GitHub for similar crashes.
https://github.com/flutter/flutter/issues?q=is%3Aissue+JSON-RPC+error+111%3A+Service+already+registered
To report your crash to the Flutter team, first read the guide to filing a bug.
https://flutter.dev/to/report-bugs
(The info below is from the URL in the tool crash output)
Command
flutter widget-preview start --dtd-url ws://127.0.0.1:53214/Ot7rKr-RbaU=Steps to Reproduce
- Open the widget preview in VS Code
- Copy the DTD URI (from the command palette of language status area)
- Run
flutter widget-preview start --dtd-url ws://127.0.0.1:53214/xxxxxx=(replacing this URI with the one you copied)
Logs
RpcException
package:json_rpc_2/src/client.dart 122:62 Client.sendRequest
package:json_rpc_2/src/peer.dart 98:15 Peer.sendRequest
package:dtd/src/dart_tooling_daemon.dart 106:23 DartToolingDaemon.registerService
package:flutter_tools/src/widget_preview/dtd_services.dart 161:14 WidgetPreviewDtdServices._registerServices
package:flutter_tools/src/widget_preview/dtd_services.dart 120:11 WidgetPreviewDtdServices.connect
===== asynchronous gap ===========================
package:flutter_tools/src/commands/widget_preview.dart 402:7 WidgetPreviewStartCommand.configureDtd
===== asynchronous gap ===========================
package:flutter_tools/src/commands/widget_preview.dart 359:5 WidgetPreviewStartCommand.runCommand
===== asynchronous gap ===========================
package:flutter_tools/src/runner/flutter_command.dart 1564:27 FlutterCommand.run.<fn>
===== asynchronous gap ===========================
package:flutter_tools/src/base/context.dart 154:19 AppContext.run.<fn>
===== asynchronous gap ===========================
package:args/command_runner.dart 212:13 CommandRunner.runCommand
===== asynchronous gap ===========================
package:flutter_tools/src/runner/flutter_command_runner.dart 487:9 FlutterCommandRunner.runCommand.<fn>
===== asynchronous gap ===========================
package:flutter_tools/src/base/context.dart 154:19 AppContext.run.<fn>
===== asynchronous gap ===========================
package:flutter_tools/src/runner/flutter_command_runner.dart 422:5 FlutterCommandRunner.runCommand
===== asynchronous gap ===========================
package:flutter_tools/runner.dart 104:11 run.<fn>.<fn>
===== asynchronous gap ===========================
package:flutter_tools/src/base/context.dart 154:19 AppContext.run.<fn>�[33m[!]�[39m Flutter (Channel master, 3.40.0-1.0.pre-105, on Microsoft Windows [Version 10.0.26100.7462], locale en-GB) [3.3s]
�[32m•�[39m Flutter version 3.40.0-1.0.pre-105 on channel master at D:\Dev\Google\Flutter\Flutter main
�[33m!�[39m Warning: `dart` on your path resolves to D:\Tools\Dart\Stable\bin\dart.exe, which is not inside your current Flutter SDK checkout at
D:\Dev\Google\Flutter\Flutter main. Consider adding D:\Dev\Google\Flutter\Flutter main\bin to the front of your path.
�[33m!�[39m Upstream repository git@github.com:DanTup/flutter.git is not a standard remote.
Set environment variable "FLUTTER_GIT_URL" to git@github.com:DanTup/flutter.git to dismiss this error.
�[32m•�[39m Framework revision 6519f99911 (5 days ago), 2025-12-10 00:18:27 -0500
�[32m•�[39m Engine revision 6519f99911
�[32m•�[39m Dart version 3.11.0 (build 3.11.0-227.0.dev)
�[32m•�[39m DevTools version 2.53.0
�[32m•�[39m Feature flags: enable-web, enable-linux-desktop, enable-macos-desktop, enable-windows-desktop, enable-android, enable-ios, cli-animations,
enable-native-assets, omit-legacy-version-file, enable-lldb-debugging, enable-uiscene-migration
�[32m•�[39m If those were intentional, you can disregard the above warnings; however it is recommended to use "git" directly to perform update checks and
upgrades.
�[32m[✓]�[39m Windows Version (11 Pro 64-bit, 24H2, 2009) [835ms]
�[33m[!]�[39m Android toolchain - develop for Android devices (Android SDK version 35.0.0) [1,814ms]
�[32m•�[39m Android SDK at C:\Users\danny\AppData\Local\Android\sdk
�[32m•�[39m Emulator version 35.4.9.0 (build_id 13025442) (CL:N/A)
�[32m•�[39m Platform android-36, build-tools 35.0.0
�[32m•�[39m Java binary at: C:\Program Files\Android\Android Studio\jbr\bin\java
This is the JDK bundled with the latest Android Studio installation on this machine.
To manually set the JDK path, use: `flutter config --jdk-dir="path/to/jdk"`.
�[32m•�[39m Java version OpenJDK Runtime Environment (build 21.0.6+-13355223-b631.42)
�[33m!�[39m Some Android licenses not accepted. To resolve this, run: flutter doctor --android-licenses
�[32m[✓]�[39m Chrome - develop for the web [55ms]
�[32m•�[39m Chrome at C:\Program Files\Google\Chrome\Application\chrome.exe
�[32m[✓]�[39m Visual Studio - develop Windows apps (Visual Studio Community 2022 17.10.5) [54ms]
�[32m•�[39m Visual Studio at C:\Program Files\Microsoft Visual Studio\2022\Community
�[32m•�[39m Visual Studio Community 2022 version 17.10.35122.118
�[32m•�[39m Windows 10 SDK version 10.0.26100.0
�[32m[✓]�[39m Connected device (3 available) [88ms]
�[32m•�[39m Windows (desktop) • windows • windows-x64 • Microsoft Windows [Version 10.0.26100.7462]
�[32m•�[39m Chrome (web) • chrome • web-javascript • Google Chrome 143.0.7499.40
�[32m•�[39m Edge (web) • edge • web-javascript • Microsoft Edge 143.0.3650.75
�[32m[✓]�[39m Network resources [554ms]
�[32m•�[39m All expected network resources are available.
�[33m!�[39m Doctor found issues in 2 categories.
Flutter Application Metadata
Type: malformed
Version: 0.0.1
Material: true
Android X: false
Module: false
Plugin: false
Android package: null
iOS bundle identifier: null
Creation channel: null
Creation framework version: null
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Important issues not at the top of the work listError messages from the Flutter frameworkIssues related to the Widget Previewer toolingStack traces logged to the consoleCrashes that terminate the processFound to occur in 3.38Found to occur in 3.40The issue has been confirmed reproducible and is ready to work onIssue is closed as already fixed in a newer versionOwned by Flutter Tool teamAffects the "flutter" command-line tool. See also t: labels.Triaged by Flutter Tool team