Fails to start – Unable to open X display / Failed to connect to Wayland display

Flatpak app `com.visualstudio.code` fails to start on my system, both in X11 and Wayland mode, even with `--no-sandbox` and/or `ZYPAK_DISABLE_SANDBOX=1`. I also tried #271, but it behaves identically. However, [com.visualstudio.code-oss](https://github.com/flathub/com.visualstudio.code-oss) starts without any problem in both X11 and Wayland mode. Other Electron-based Flatpak apps also work without problem.

```
$ flatpak run com.visualstudio.code --verbose
[2 preload-host-spawn-strategy] Running: /app/bin/zypak-helper child - /app/extra/vscode/code --type=zygote
[2:0130/212424.506496:ERROR:browser_main_loop.cc(1402)] Unable to open X display.
The futex facility returned an unexpected error code.
```

```
$ flatpak override --socket=wayland com.visualstudio.code
$ flatpak run com.visualstudio.code --enable-features=UseOzonePlatform --ozone-platform=wayland --verbose
Warning: 'enable-features' is not in the list of known options, but still passed to Electron/Chromium.
Warning: 'ozone-platform' is not in the list of known options, but still passed to Electron/Chromium.
[2 preload-host-spawn-strategy] Running: /app/bin/zypak-helper child - /app/extra/vscode/code --type=zygote
[2:0130/213001.214324:ERROR:wayland_connection.cc(127)] Failed to connect to Wayland display
[2:0130/213001.214368:FATAL:ozone_platform_wayland.cc(173)] Failed to initialize Wayland platform
```

$ ZYPAK_DEBUG=1 flatpak run com.visualstudio.code --enable-features=UseOzonePlatform --ozone-platform=wayland --verbose
(click here to expand…)

[2 zypak-helper] Determining sandbox strategy...

[2 zypak-helper] Added task source 0x55a259a362e0

[2 zypak-helper] Lifting task 0x55a259a362e0 to trigger

[2 zypak-helper] Added task source 0x55a259a36570

[2 zypak-helper] Lifting task 0x55a259a36570 to trigger

[2 zypak-helper] D-Bus watch add 3 with flags 1

[2 zypak-helper] Adding I/O source 0x55a259a367d0 for 3

[2 zypak-helper] Added task source 0x55a259a36c20

[2 zypak-helper] Pumping bus thread

[2 zypak-helper] Begin dispatch

[2 zypak-helper] Received event from 0x55a259a36c20

[2 zypak-helper] Added timer source 0x7fec700010d0 with duration 25000ms

[2 zypak-helper] Pumping bus thread

[2 zypak-helper] Begin dispatch

[2 zypak-helper] Received event from 0x55a259a367d0

[2 zypak-helper] Incoming events on D-Bus watch 3: 1

[2 zypak-helper] Disable source 0x7fec700010d0

[2 zypak-helper] Got D-Bus wake request

[2 zypak-helper] Trigger source 0x55a259a36570

[2 zypak-helper] Pumping bus thread

[2 zypak-helper] Begin dispatch

[2 zypak-helper] Received event from 0x55a259a36570

[2 zypak-helper] Dispatching on bus thread

[2 zypak-helper] CallAsync returned

[2 zypak-helper] Got D-Bus dispatch status

[2 zypak-helper] Pumping bus thread

[2 zypak-helper] Added task source 0x55a259a37090

[2 zypak-helper] Begin dispatch

[2 zypak-helper] Received event from 0x55a259a37090

[2 zypak-helper] Added timer source 0x55a259a36c20 with duration 25000ms

[2 zypak-helper] Pumping bus thread

[2 zypak-helper] Begin dispatch

[2 zypak-helper] Received event from 0x55a259a367d0

[2 zypak-helper] Incoming events on D-Bus watch 3: 1

[2 zypak-helper] Disable source 0x55a259a36c20

[2 zypak-helper] Got D-Bus wake request

[2 zypak-helper] Trigger source 0x55a259a36570

[2 zypak-helper] Got D-Bus dispatch status

[2 zypak-helper] Trigger source 0x55a259a36570

[2 zypak-helper] Pumping bus thread

[2 zypak-helper] Begin dispatch

[2 zypak-helper] Received event from 0x55a259a36570

[2 zypak-helper] Dispatching on bus thread

[2 zypak-helper] CallAsync returned

[2 zypak-helper] Got D-Bus dispatch status

[2 zypak-helper] Pumping bus thread

[2 zypak-helper] Shutting down bus thread...

[2 zypak-helper] Trigger source 0x55a259a362e0

[2 zypak-helper] Begin dispatch

[2 zypak-helper] Received event from 0x55a259a362e0

[2 zypak-helper] Bus thread shutdown complete

[2 zypak-helper] D-Bus watch remove 3

[2 zypak-helper] Disable source 0x55a259a367d0

[2 zypak-helper] D-Bus watch remove 3

[2 zypak-helper] Got D-Bus wake request

[2 zypak-helper] Trigger source 0x55a259a36570

[2 zypak-helper] Got D-Bus dispatch status

[2 zypak-helper] Trigger source 0x55a259a36570

[2 zypak-helper] Spawn strategy is enabled

[2 zypak-helper] Preload is: /app/bin/../lib/libzypak-preload-host.so:/app/bin/../lib/libzypak-preload-host-spawn-strategy.so

[2 zypak-helper] /app/extra/vscode/code /app/extra/vscode/resources/app/out/cli.js --ms-enable-electron-run-as-node --extensions-dir=/home/xxx/.var/app/com.visualstudio.code/data/vscode/extensions --enable-features=UseOzonePlatform --ozone-platform=wayland --verbose

[2 preload-host-spawn-strategy] Added task source 0x33271d39ad80

[2 preload-host-spawn-strategy] Lifting task 0x33271d39ad80 to trigger

[2 preload-host-spawn-strategy] Added task source 0x33271d39ac60

[2 preload-host-spawn-strategy] Lifting task 0x33271d39ac60 to trigger

[2 preload-host-spawn-strategy] D-Bus watch add 3 with flags 1

[2 preload-host-spawn-strategy] Adding I/O source 0x33271d39ab40 for 3

[2 preload-host-spawn-strategy] Pumping bus thread

[2 preload-host-spawn-strategy] Adding I/O source 0x33271d39aa20 for 6

[2 preload-host-spawn-strategy] Added task source 0x33271d39a900

[2 preload-host-spawn-strategy] Begin dispatch

[2 preload-host-spawn-strategy] Received event from 0x33271d39a900

[2 preload-host-spawn-strategy] Added timer source 0x33271d39a7e0 with duration 25000ms

[2 preload-host-spawn-strategy] Disable source 0x33271d39a7e0

[2 preload-host-spawn-strategy] Got D-Bus wake request

[2 preload-host-spawn-strategy] Trigger source 0x33271d39ac60

[2 preload-host-spawn-strategy] Pumping bus thread

[2 preload-host-spawn-strategy] Begin dispatch

[2 preload-host-spawn-strategy] Received event from 0x33271d39ac60

[2 preload-host-spawn-strategy] Dispatching on bus thread

[2 preload-host-spawn-strategy] Got D-Bus dispatch status

[2 preload-host-spawn-strategy] Pumping bus thread

Warning: 'enable-features' is not in the list of known options, but still passed to Electron/Chromium.

Warning: 'ozone-platform' is not in the list of known options, but still passed to Electron/Chromium.

[2 preload-host-spawn-strategy] Prepare for fork

[2 preload-host-spawn-strategy] Shutting down bus thread...

[2 preload-host-spawn-strategy] Trigger source 0x33271d39ad80

[2 preload-host-spawn-strategy] Begin dispatch

[2 preload-host-spawn-strategy] Received event from 0x33271d39ad80

[2 preload-host-spawn-strategy] Bus thread shutdown complete

[2 preload-host-spawn-strategy] Resume bus in parent

[2 preload-host-spawn-strategy] Pumping bus thread

[22 zypak-helper] Added task source 0x561006682f90

[22 zypak-helper] Lifting task 0x561006682f90 to trigger

[22 zypak-helper] Added task source 0x5610066835c0

[22 zypak-helper] Lifting task 0x5610066835c0 to trigger

[22 zypak-helper] D-Bus watch add 3 with flags 1

[22 zypak-helper] Adding I/O source 0x561006683820 for 3

[22 zypak-helper] Spawn latest of /app/bin/zypak-helper host /app/extra/vscode/code --extensions-dir=/home/jirutjak/.var/app/com.visualstudio.code/data/vscode/extensions --enable-features=UseOzonePlatform --ozone-platform=wayland --in-process-gpu --verbose

[22 zypak-helper] Pumping bus thread

[22 zypak-helper] Added task source 0x561006684a40

[22 zypak-helper] Begin dispatch

[22 zypak-helper] Received event from 0x561006684a40

[22 zypak-helper] Added timer source 0x7f2ec80010d0 with duration 25000ms

[22 zypak-helper] Pumping bus thread

[22 zypak-helper] Begin dispatch

[22 zypak-helper] Received event from 0x561006683820

[22 zypak-helper] Incoming events on D-Bus watch 3: 1

[22 zypak-helper] Disable source 0x7f2ec80010d0

[22 zypak-helper] Got D-Bus wake request

[22 zypak-helper] Trigger source 0x5610066835c0

[22 zypak-helper] Pumping bus thread

[22 zypak-helper] Begin dispatch

[22 zypak-helper] Received event from 0x5610066835c0

[22 zypak-helper] Dispatching on bus thread

[22 zypak-helper] CallAsync returned

[22 zypak-helper] Got D-Bus dispatch status

[22 zypak-helper] Pumping bus thread

[2 preload-host-spawn-strategy] waitpid(22)

[2 preload-host-spawn-strategy] Can't find stub pid data 22

[2 preload-host-spawn-strategy] Could not find stub pid data for 22

[2 preload-host-spawn-strategy] Running: /app/bin/zypak-helper child - /app/extra/vscode/code --type=zygote

[2:0130/213034.692073:ERROR:wayland_connection.cc(127)] Failed to connect to Wayland display

[2:0130/213034.692107:FATAL:ozone_platform_wayland.cc(173)] Failed to initialize Wayland platform

```
$ env
DISPLAY=:0
XDG_RUNTIME_DIR=/run/user/1000
XDG_SESSION_TYPE=wayland
WAYLAND_DISPLAY=wayland-1
...
```

* * *
**Environment:**
- Alpine Linux v3.15 on x86_64
- Sway 1.6.1
- Flatpak 1.12.3
- com.visualstudio.code 1.60.2

Start by reproducing the failure with `flatpak run com.visualstudio.code --verbose` in both X11 and Wayland, then compare the result with `com.visualstudio.code-oss`, which reportedly works. Review the reported Zypak and display-connection output; done means the VS Code Flatpak starts successfully in both display modes on the stated environment.

索引モデルが issue の本文から書いたものです。