Failed to unregister class Chrome_WidgetWin_0. Error = 203


I am using Elixir Desktop (by @dominicletz ) to make an elixir desktop application:

And I am successfully able to launch and manage my app. However, when I close it I always get this error:

[1224/] Failed to unregister class Chrome_WidgetWin_0. Error = 203



There are actually two issues here

  1. The application takes a very long time to close after I press Quit. The message is received by Phoenix (see the I AM LEAVING log) but for some reason the window takes several seconds to close.
  2. I get the previously mentioned error


At this point 90% of this HelloWorld project is code generated by mix. There are only 2 files I changes that might be relevant here:


defmodule WebInterface.MenuBar do
  @moduledoc """
    Menubar that is shown as part of the main Window on Windows/Linux. In
    MacOS this Menubar appears at the very top of the screen.
  import WebInterface.Gettext
  use Desktop.Menu
  alias Desktop.Window

  @impl Desktop.Menu
  def render(assigns) do
      <menu label={gettext("File")}>
          <item onclick="quit"><%= gettext "Quit" %></item>
      <menu label={gettext("Extra")}>
          <item onclick="browser"><%= gettext "Open Browser" %></item>

  @impl Desktop.Menu
  def handle_event("quit", menu) do
    IO.puts("I AM LEAVING")
    {:noreply, menu}

  def handle_event("browser", menu) do
    |> Window.prepare_url()
    |> :wx_misc.launchDefaultBrowser()

    {:noreply, menu}

  @impl Desktop.Menu
  def mount(menu) do
    {:ok, menu}

  @impl Desktop.Menu
  def handle_info(:changed, menu) do
    {:noreply, menu}


defmodule WebInterface.Application do
  # See
  # for more information on OTP Applications
  @moduledoc false

  use Application

    alias Desktop

  @impl true
  def start(_type, _args) do
    children = [
      {Phoenix.PubSub, name: WebInterface.PubSub},
         app: :web_interface,
         id: WebInterface,
         title: "Web Interface",
         size: {600, 500},
         menubar: WebInterface.MenuBar,
         url: &WebInterface.Endpoint.url/0

    opts = [strategy: :one_for_one, name: WebInterface.Supervisor]
    Supervisor.start_link(children, opts)

  @impl true
  def config_change(changed, _new, removed) do
    WebInterface.Endpoint.config_change(changed, removed)

I am hoping this error is caused by either a miss configuration or some function I am not implementing correctly.

How can I fix this error?

1 Like

I’ve definitely seen this before but thought it to be something in my app. Thanks for this minimal example. I’ll have a look into this sometime next week


For convience’s sake, here is the MWE app:

PS: I have added bakeware (GitHub - bake-bake-bake/bakeware: Compile Elixir applications into single, easily distributed executable binaries) to the app. It is optional, but it replicates the issue in the exe file, so I think it can be a good point of reference as well.

And thank you for having a look at this!

The only thing I found was this old post for 2016:

Not sure what to do with it to be honest, specially when I don’t even have Chrome on my VM, I only use Firefox.

1 Like

@dominicletz Hey there, did you have some time to check the application out? If there is something I can do to help (that fits my limited ability within this domain) please do share!

1 Like

Well I did push an update to elixir-desktop that should cause the app now to instantly close. Please check that out and let me know if it works

Is it in the tag v1.4.0?

Or directly in the master branch ?

Hey I tested with master. I can confirm the application now closes faster, however there are still 2 issues:

  1. If I go to File -> Quit, the application still get the error:
[0114/] Failed to unregister class Chrome_WidgetWin_0. Error = 0
  1. If I close the app by pressing the X on the top right corner I get a crash:
03:11:29.145 [notice] Application web_interface exited: shutdown
{"Kernel pid terminated",application_controller,"{application_terminated,web_interface,shutdown}"}
Kernel pid terminated (application_controller) ({application_terminated,web_interface,shutdown})

Crash dump is being written to: erl_crash.dump...done
[0114/] Failed to unregister class Chrome_WidgetWin_0. Error = 0

It could be because I am running in PROD, perhaps the crash happens due to a missconfig, but I have no data to support that.

Additionally, it looks like the process takes quite a time to exit. Not sure why.

So in 1) it’s closing immediately but in 2) it just crashes? I’ll check what’s going on there.

Unfortunately the error message is coming directly from chrome 113008 - chromium - An open-source project to help move the web forward. - Monorail and is a know open issue. I don’t see an immediate way to get rid of it.

1 Like

I feel there is nothing else o be done here. I will close this answer as your PR to master did fix the main issue.
Feel free to let me know when a new release is coming :smiley:

I have also just noticed that you now have it on hexpm !