"show GUI" button doesn't work for Carla on Linux

[Duskhorn]

Bug Summary

Carla (both rack and patchbay) doesn't load when clicking on the "show GUI"

Steps to reproduce

Clicking the "Show GUI" button in the synth menu

Expected behavior

Carla opens and loads correctly

Actual behavior

Carla doesn't open. Debug console displays

Trying to start carla-plugin using "//share/carla/resources/carla-plugin"
exec failed: No such file or directory
waitForClientFirstMessage() - read returned 0

Affected LMMS versions

1.2.2 64bit Linux AppImage downloaded from the official website

[mikobuntu]

@Duskhorn Works ok for me , are you sure that you have carla installed on your system ? I believe that the carla plugins in LMMS are just a frontend for the system version of carla.

[PhysSong]

Further inspection on Discord(with LD_DEBUG=files):

      1553:    file=libcarla_native-plugin.so [0];  needed by /tmp/.mount_lmms.A2S5rLy/usr/lib/lmms/libcarlabase.so [0]
      1553:    file=libcarla_native-plugin.so [0];  generating link map
      1553:    file=libfluidsynth.so.3 [0];  needed by /lib/carla/libcarla_native-plugin.so [0]
      1553:    file=liblo.so.7 [0];  needed by /lib/carla/libcarla_native-plugin.so [0]
      1553:    file=libmagic.so.1 [0];  needed by /lib/carla/libcarla_native-plugin.so [0]
      1553:    calling init: /lib/carla/libcarla_native-plugin.so

For some reason, Carla is loaded from /lib(not from /usr/lib as in usual cases) and causing issues because /lib/../share is /share.

[Nefor111]

Arch Linux
Lmms 1.2.2
carla-git from AUR repository

Well the problem is - then "show GUI" key is pressed

carla] Trying to start carla-plugin using "/usr/share/carla/resources/carla-plugin"
Traceback (most recent call last):
File "/usr/share/carla/resources/carla-plugin", line 29, in
from carla_host import *
File "/usr/share/carla/resources/carla_host.py", line 53, in
import ui_carla_host
File "/usr/share/carla/resources/ui_carla_host.py", line 848, in
from widgets.racklistwidget import RackListWidget
File "/usr/share/carla/resources/widgets/racklistwidget.py", line 36, in
from carla_skin import createPluginSlot
File "/usr/share/carla/resources/carla_skin.py", line 37, in
from carla_widgets import *
File "/usr/share/carla/resources/carla_widgets.py", line 96, in
from widgets.pixmapkeyboard import PixmapKeyboardHArea
File "/usr/share/carla/resources/widgets/pixmapkeyboard.py", line 29, in
from utils import QSafeSettings
ModuleNotFoundError: No module named 'utils'
[carla] waitForClientFirstMessage() - read returned 0

Then installed module utils via pip3 install utils following errors appear

[carla] Trying to start carla-plugin using "/usr/share/carla/resources/carla-plugin"
Traceback (most recent call last):
File "/usr/share/carla/resources/carla-plugin", line 29, in
from carla_host import *
File "/usr/share/carla/resources/carla_host.py", line 53, in
import ui_carla_host
File "/usr/share/carla/resources/ui_carla_host.py", line 848, in
from widgets.racklistwidget import RackListWidget
File "/usr/share/carla/resources/widgets/racklistwidget.py", line 36, in
from carla_skin import createPluginSlot
File "/usr/share/carla/resources/carla_skin.py", line 37, in
from carla_widgets import *
File "/usr/share/carla/resources/carla_widgets.py", line 96, in
from widgets.pixmapkeyboard import PixmapKeyboardHArea
File "/usr/share/carla/resources/widgets/pixmapkeyboard.py", line 29, in
from utils import QSafeSettings
ImportError: cannot import name 'QSafeSettings' from 'utils' (/home/neff/.local/lib/python3.10/site-packages/utils/init.py)
[carla] waitForClientFirstMessage() - read returned 0

Stand alone version is working without any issue.

[Arnesfield]

Also experienced the same issue by @Nefor111. I don't have experience with Python, but I was able to resolve the issue by creating symlinks pointing to utils and pluginlist in the resources directory.

Go to resources:

cd /usr/share/carla/resources

Create symlink to utils:

sudo ln -s ../utils utils

Doing this fixes the from utils import QSafeSettings error, but it shows a new error with pluginlist:

[carla] Trying to start carla-plugin using "/usr/share/carla/resources/carla-plugin-patchbay"
Traceback (most recent call last):
  File "/usr/share/carla/resources/carla-plugin-patchbay", line 29, in <module>
    from carla_host import *
  File "/usr/share/carla/resources/carla_host.py", line 64, in <module>
    from pluginlist import PluginDatabaseW
ModuleNotFoundError: No module named 'pluginlist'
[carla] waitForClientFirstMessage() - read returned 0

Fixed by also creating a symlink pointing to pluginlist within resources:

sudo ln -s ../pluginlist pluginlist

"Show GUI" works now after creating these symlinks.

I assume this is a workaround rather than an actual fix. I'd be happy if there's a better solution, but until the issue is resolved, hope this workaround helps.