lemonade-server fails to start on Linux due to FLM check (NotADirectoryError)

[Ploux]

Environment

• OS: Linux (Pop!_OS/Ubuntu)
• Python: 3.10
• GPU: Nvidia 5090

Issue

When starting lemonade-server on Linux, it crashes trying to check for FLM models, even though FLM is Windows-only?

Error

INFO:     127.0.0.1:33752 - "GET /api/server-running-status HTTP/1.1" 200 OK
2025-10-08 21:02:51,022 - infinity_arcade.main - INFO - === Server running status endpoint called ===
2025-10-08 21:02:51,023 - infinity_arcade.main - INFO - Checking if lemonade-server is running...
2025-10-08 21:02:51,023 - infinity_arcade.main - INFO - Executing lemonade-server command with args: ['status']
2025-10-08 21:02:51,023 - infinity_arcade.main - INFO - Trying command 1: ['lemonade-server-dev', 'status']
2025-10-08 21:02:51,181 - infinity_arcade.main - INFO - Status output: 'Server is not running'
2025-10-08 21:02:51,181 - infinity_arcade.main - INFO - Server is not running according to status command
2025-10-08 21:02:51,181 - infinity_arcade.main - INFO - Initial running check result: False
2025-10-08 21:02:51,181 - infinity_arcade.main - INFO - Server not running, attempting to start automatically...
2025-10-08 21:02:51,181 - infinity_arcade.main - INFO - Attempting to start lemonade-server...
2025-10-08 21:02:51,191 - infinity_arcade.main - INFO - Executing lemonade-server command with args: ['serve', '--ctx-size', '16384']
2025-10-08 21:02:51,191 - infinity_arcade.main - INFO - Trying command 1: ['lemonade-server-dev', 'serve', '--ctx-size', '16384']
2025-10-08 21:02:52,196 - infinity_arcade.main - ERROR - Server failed immediately. Return code: 1
2025-10-08 21:02:52,196 - infinity_arcade.main - ERROR - Stderr: Traceback (most recent call last):
  File "/home/ruin/.local/bin/lemonade-server-dev", line 8, in <module>
    sys.exit(main())
  File "/home/ruin/.local/lib/python3.10/site-packages/lemonade_server/cli.py", line 727, in main
    serve(
  File "/home/ruin/.local/lib/python3.10/site-packages/lemonade_server/cli.py", line 83, in serve
    server = Server(
  File "/home/ruin/.local/lib/python3.10/site-packages/lemonade/tools/server/serve.py", line 305, in __init__
    self.local_models = ModelManager().downloaded_models_enabled
  File "/home/ruin/.local/lib/python3.10/site-packages/lemonade_server/model_manager.py", line 156, in downloaded_models_enabled
    return self.filter_models_by_backend(self.downloaded_models)
  File "/home/ruin/.local/lib/python3.10/site-packages/lemonade_server/model_manager.py", line 95, in downloaded_models
    flm_installed_checkpoints = get_flm_installed_models()
  File "/home/ruin/.local/lib/python3.10/site-packages/lemonade/tools/flm/utils.py", line 214, in get_flm_installed_models
    result = subprocess.run(
  File "/usr/lib/python3.10/subprocess.py", line 503, in run
    with Popen(*popenargs, **kwargs) as process:
  File "/usr/lib/python3.10/subprocess.py", line 971, in __init__
    self._execute_child(args, executable, preexec_fn, close_fds,
  File "/usr/lib/python3.10/subprocess.py", line 1863, in _execute_child
    raise child_exception_type(errno_num, err_msg, err_filename)
NotADirectoryError: [Errno 20] Not a directory: 'flm'
2025-10-08 21:02:52,196 - infinity_arcade.main - INFO - Stdout: Starting Lemonade Server...
2025-10-08 21:02:52,197 - infinity_arcade.main - INFO - Auto-start result: {'success': False, 'message': 'Server process died immediately'}
2025-10-08 21:02:52,197 - infinity_arcade.main - WARNING - Auto-start failed: Unknown error
2025-10-08 21:02:52,197 - infinity_arcade.main - INFO - === Returning server running status: {'running': False} ===

Expected Behavior

lemonade-server should gracefully handle FLM not being available on Linux systems and skip the FLM model check.

Reproduction

• install (either via pypi or source)
• run infinity-arcade
• lemonade server v8.1.12 installs
• 2nd step Server status fails: Lemonade Server failed to start within 16 seconds

[jeremyfowers]

Thanks for filing the issue @Ploux!

I just tried this a three different ways on my Ubuntu RAI 370 HX laptop and it worked fine... which scares me. Also works fine in Infinity Arcade's ubuntu CI.

Something about your OS is raising a NotADirectoryError. I can just add that to the set of exceptions that indicate FLM is not installed: lemonade-sdk/lemonade#452

Do mind trying that branch to see if it fixes you @Ploux?

git clone https://github.com/lemonade-sdk/lemonade.git
cd lemonade
git checkout bug/linux-flm
pip install -e .
infinity-arcade

[Ploux]

Great, that got it working.

I had to create a virtual environment, and then navigate back to the original directory to run infinity arcade (might want to mention venv in the install instructions):

git clone https://github.com/lemonade-sdk/lemonade.git
cd lemonade
git checkout bug/linux-flm
python3 -m venv venv 
source venv/bin/activate
pip install -e .
cd ~/infinity-arcade
infinity-arcade

[jeremyfowers]

Thanks for reporting back! I’ll merge the fix into Lemonade.