DevTools fails to launch with a confusing message if Chrome is not installed

[g-yashwanth]

I was running app and asked me to

activate DevTools I just did it in vs code and some process was running and it popped up saying "The DevTools service failed to launch the browser. Please raise a bug against the Dart extension for VS Code. " and showed a bug report which is :

Failed to launch browser: ProcessException: The system cannot find the file specified.

Command: .\Google\Chrome\Application\chrome.exe http://127.0.0.1:56770/?hide=debugger&ide=VSCode&theme=dark&uri=http%3A%2F%2F127.0.0.1%3A57377%2FSVM_pXxEAVY%3D%2F
#0 Chrome._startProcess (package:browser_launcher/src/chrome.dart:128:12)

#1 Chrome.start (package:browser_launcher/src/chrome.dart:120:11)

#2 registerLaunchDevToolsService. (package:devtools_server/src/server.dart:238:24)

#3 VmService._routeRequest (package:vm_service_lib/vm_service_lib.dart:1631:39)

#4 VmService._processRequest (package:vm_service_lib/vm_service_lib.dart:1609:25)

#5 VmService._processMessageStr (package:vm_service_lib/vm_service_lib.dart:1577:9)
#6 VmService._processMessage (package:vm_service_lib/vm_service_lib.dart:1535:7)
#7 _RootZone.runUnaryGuarded (dart:async/zone.dart:1314:10)
#8 _BufferingStreamSubscription._sendData (dart:async/stream_impl.dart:336:11)
#9 _BufferingStreamSubscription._add (dart:async/stream_impl.dart:263:7)
#10 _SyncBroadcastStreamController._sendData (dart:async/broadcast_stream_controller.dart:375:20)
#11 _BroadcastStreamController.add (dart:async/broadcast_stream_controller.dart:250:5)
#12 _AsBroadcastStreamController.add (dart:async/broadcast_stream_controller.dart:474:11)
#13 _RootZone.runUnaryGuarded (dart:async/zone.dart:1314:10)
#14 _BufferingStreamSubscription._sendData (dart:async/stream_impl.dart:336:11)
#15 _BufferingStreamSubscription._add (dart:async/stream_impl.dart:263:7)
#16 _SyncStreamController._sendData (dart:async/stream_controller.dart:764:19)
#17 _StreamController._add (dart:async/stream_controller.dart:640:7)
#18 _StreamController.add (dart:async/stream_controller.dart:586:5)
#19 new _WebSocketImpl._fromSocket. (dart:_http/websocket_impl.dart:1138:21)
#20 _RootZone.runUnaryGuarded (dart:async/zone.dart:1314:10)
#21 _BufferingStreamSubscription._sendData (dart:async/stream_impl.dart:336:11)
#22 _BufferingStreamSubscription._add (dart:async/stream_impl.dart:263:7)
#23 _SinkTransformerStreamSubscription._add (dart:async/stream_transformers.dart:68:11)
#24 _EventSinkWrapper.add (dart:async/stream_transformers.dart:15:11)
#25 _WebSocketProtocolTransformer._messageFrameEnd (dart:_http/websocket_impl.dart:334:22)
#26 _WebSocketProtocolTransformer.add (dart:_http/websocket_impl.dart:229:46)
#27 _SinkTransformerStreamSubscription._handleData (dart:async/stream_transformers.dart:120:24)
#28 _RootZone.runUnaryGuarded (dart:async/zone.dart:1314:10)
#29 _BufferingStreamSubscription._sendData (dart:async/stream_impl.dart:336:11)
#30 _BufferingStreamSubscription._add (dart:async/stream_impl.dart:263:7)
#31 _SyncStreamController._sendData (dart:async/stream_controller.dart:764:19)
#32 _StreamController._add (dart:async/stream_controller.dart:640:7)
#33 _StreamController.add (dart:async/stream_controller.dart:586:5)
#34 _Socket._onData (dart:io-patch/socket_patch.dart:1774:41)
#35 _RootZone.runUnaryGuarded (dart:async/zone.dart:1314:10)
#36 _BufferingStreamSubscription._sendData (dart:async/stream_impl.dart:336:11)
#37 _BufferingStreamSubscription._add (dart:async/stream_impl.dart:263:7)
#38 _SyncStreamController._sendData (dart:async/stream_controller.dart:764:19)
#39 _StreamController._add (dart:async/stream_controller.dart:640:7)
#40 _StreamController.add (dart:async/stream_controller.dart:586:5)
#41 new _RawSocket. (dart:io-patch/socket_patch.dart:1323:33)
#42 _NativeSocket.issueReadEvent.issue (dart:io-patch/socket_patch.dart:844:14)
#43 _microtaskLoop (dart:async/schedule_microtask.dart:41:21)
#44 _startMicrotaskLoop (dart:async/schedule_microtask.dart:50:5)
#45 _runPendingImmediateCallback (dart:isolate-patch/isolate_patch.dart:115:13)
#46 _RawReceivePortImpl._handleMessage (dart:isolate-patch/isolate_patch.dart:172:5)

[DanTup]

Do you have Chrome installed? If so, what's the location it's installed at?

[g-yashwanth]

no chrome isn't installed I use Mozilla, Will it only work on chrome, can't it work with Mozilla, cant we configure it

[DanTup]

Unfortunately Dart DevTools currently only supports Chrome. There's some discussion about this at flutter/devtools#492 and related issues. The browser launching is done by DevTools itself, so not something that can be configured here.

If DevTools gets support for other browsers in future, I'll update the VS Code extension to take advantage of it.

[DanTup]

I've tweaked this message to say "Dart DevTools was unable to launch Chrome" so it's clearer what's gone wrong.

I'll update this if DevTools gets support for other browsers.

[yanshouwang]

Is Microsoft's Edge insider which uses the chormium able to launch the DevTools? @DanTup

[DanTup]

I don't know enough to say whether it'd work - for example Brave is also based on Chromium but has issues rendering the tree (due to blocking measureString on canvas). There's a little more info about the details of how this works at #1760 (comment).

[ghost]

I have chrome installed and I get this message on Manjaro Linux (based on Arch Linux) where it gets installed at /opt/google/chrome/chrome with a startup script also located at /usr/bin/google-chrome-stable.

[DanTup]

@waynebloss my guess is that browser_launcher that DevTools uses to launch the browser doesn't find your executable as it is named google-chrome-stable. I think it may be worth raising an issue in browser_launcher to see if it could search for both chrome and google-chrome-stable if that's common on Linux.

I presume that although you see this error, it falls back to launching in your default browser?

[ghost]

@DanTup Yes - chrome is my default so it just works. Thanks!

[DanTup]

Great - we fall back to launching the default browser if DevTools fails. It's worth raising an issue with browser_launcher to see if they can check for both though (assuming this is common on Linux) to avoid the warning (and also so it would continue to work if Chrome wasn't your default browser).

Another option is to just symlink chrome to google-chrome-stable, though I think it might be better if it "just worked".

[ghost]

Any idea where it's used? I searched this repo for browser_launcher and I couldn't find anything. I continued my search to find the source where this error happens and above that where it calls session.session.customRequest() however I don't see how that is mapped to the browser_launcher package.

Before I open an issue, I'd like to understand this.

[ghost]

Soft linking /usr/bin/chrome -> /usr/bin/google-chrome-stable didn't seem to work. I'll keep trying later to see what does.

[ghost]

I found it. It's trying to launch google-chrome so linking with that name works.

Failed to launch browser: ProcessException: No such file or directory
  Command: google-chrome http://127.0.0.1:9100/?hide=debugger&ide=VSCode&theme=dark&uri=http%3A%2F%2F127.0.0.1%3A38507%2F16GEBer2mu0%3D%2F
#0      Chrome._startProcess (package:browser_launcher/src/chrome.dart:130:12)
...

[DanTup]

Thanks for debugging and opening the issue. Once it's fixed in browser_launcher and that change rolls into DevTools, it should start working without the link (and without any change needed here).

Thanks!