# Cannot launch Elixir Desktop app when MIX\_ENV=test

**URL:** <https://forum.devtalk.com/t/cannot-launch-elixir-desktop-app-when-mix-env-test/128679>\
**Category:** Frontend Questions/Help\
**Tags:** elixir, liveview, desktop, phoenix\
**Created:** [16 October 2023 16:58 UTC](https://forum.devtalk.com/t/cannot-launch-elixir-desktop-app-when-mix-env-test/128679 "2023-10-16T16:58:58Z")\
**Posts on this page:** 2\
**Page:** 1

<div class="post-metadata">

**Author:** ![Fl4m3Ph03n1x](https://forum.devtalk.com/user_avatar/forum.devtalk.com/fl4m3ph03n1x/32/3808_2.png) [@Fl4m3Ph03n1x](https://forum.devtalk.com/u/Fl4m3Ph03n1x)\
**Post date:** [16 October 2023 16:58 UTC](https://forum.devtalk.com/t/cannot-launch-elixir-desktop-app-when-mix-env-test/128679/1 "2023-10-16T16:58:58Z")

</div>

## Background

I have Phoenix umbrella application. When inside said application, I can run it without issues if `MIX_ENV=prod`. However, if I do `mix test` while `MIX_ENV=dev`, I get an error.

## Problem

The error I have is as follows:

```auto
18:39:42.101 [error] ** wx object server {:local, WebInterface} terminating
** Last message in was {:"$gen_cast", {:show, &WebInterface.Endpoint.url/0}}
** When Server state == %Desktop.Window{
  module: nil,
  taskbar: nil,
  frame: {:wx_ref, 35, :wxFrame, []},
  notifications: %{},
  webview: {:wx_ref, 49, :wxWebView, []},
  home_url: &WebInterface.Endpoint.url/0,
  last_url: nil,
  title: "Market Manager",
  rebuild: 0,
  rebuild_timer: {:interval, #Reference<0.2679771817.2635857922.255366>}
}
** Reason for termination ==
** {:badarg,
 [
   {:erlang, :binary_to_existing_atom,
    ["Elixir.WebInterface.Endpoint.HTTP", :utf8],
    [error_info: %{module: :erl_erts_errors}]},
   {:elixir_aliases, :safe_concat, 1,
    [file: ~c"src/elixir_aliases.erl", line: 139]},
   {WebInterface.Endpoint, :url, 0,
    [file: ~c"lib/web_interface/endpoint.ex", line: 4]},
   {Desktop.Window, :prepare_url, 1,
    [file: ~c"lib/desktop/window.ex", line: 666]},
   {Desktop.Window, :handle_cast, 2,
    [file: ~c"lib/desktop/window.ex", line: 604]},
   {:wx_object, :handle_msg, 5, [file: ~c"wx_object.erl", line: 493]},
   {:proc_lib, :init_p_do_apply, 3, [file: ~c"proc_lib.erl", line: 241]}
 ]}

```

Reading this, I understand the problem comes from my `application.ex`, namely:

```auto
@impl true
  def start(_type, _args) do
    children = [
      Telemetry,
      {Phoenix.PubSub, name: PubSub},
      Endpoint,
      Manager,
      %{
        id: Desktop.Window,
        start:
          {Desktop.Window, :start_link,
           [
             [
               app: :web_interface,
               id: WebInterface,
               title: "Market Manager",
               size: WindowUtils.calculate_window_size(0.6, 0.8),
               menubar: MenuBar,
               icon: "static/images/resized_logo_5_32x32.png",
               url: &WebInterface.Endpoint.url/0 # This line seems to be a problem
             ]
           ]},
        restart: :transient,
        shutdown: 5_000
      }
    ]

    opts = [strategy: :one_for_one, name: WebInterface.Supervisor]

    Supervisor.start_link(children, opts)
  end

```

After reading more on the subject I changed my `config/test.exs` to this:

```auto
import Config

config :web_interface, WebInterface.Endpoint,
  http: [ip: {127, 0, 0, 1}, port: 4002],
  secret_key_base: "some_key",
  server: true,
  check_origin: false

```

But this still does not fix the issue.

In contrast, this is my `config/prod.exs`:

```auto
config :web_interface, WebInterface.Endpoint,
  http: [ip: {127, 0, 0, 1}, port: 80],
  cache_static_manifest: "priv/static/cache_manifest.json",
  secret_key_base: "some_key",
  check_origin: false,
  server: true

```

But the issue still occurs.

## Questions

- Why am I having this issue?
- How can I fix it?

---

<div class="post-metadata">

**Author:** ![Fl4m3Ph03n1x](https://forum.devtalk.com/user_avatar/forum.devtalk.com/fl4m3ph03n1x/32/3808_2.png) [@Fl4m3Ph03n1x](https://forum.devtalk.com/u/Fl4m3Ph03n1x)\
**Post date:** [20 October 2023 08:09 UTC](https://forum.devtalk.com/t/cannot-launch-elixir-desktop-app-when-mix-env-test/128679/2 "2023-10-20T08:09:46Z")

</div>

## Answer

Turns out that in a previous launch of the application, wxWidgets (the process) had exited in a bad state. Perhaps it crashed or something else happened, but what matters here is that trying to restart it was impossible.

I had to restart my machine to start everything in a new clean state.  
I also deleted the `_build` folder to be sure.

This solved the issue.