Failed to load model: HTTP 422

[Ploux]

Ubuntu 22.04, 4090 mobile (16 GB VRAM), pip install

INFO:     127.0.0.1:42988 - "GET /api/model-installation-status HTTP/1.1" 200 OK
2025-08-26 15:07:13,601 - lemonade_arcade.main - INFO - Model loading status endpoint called
2025-08-26 15:07:13,601 - lemonade_arcade.main - INFO - Checking if model is loaded: Qwen3-Coder-30B-A3B-Instruct-GGUF
2025-08-26 15:07:13,632 - lemonade_arcade.main - INFO - Model loaded status: False, current model: None
2025-08-26 15:07:13,632 - lemonade_arcade.main - INFO - Model loaded check result: {'loaded': False, 'model_name': 'Qwen3-Coder-30B-A3B-Instruct-GGUF', 'current_model': None}
2025-08-26 15:07:13,632 - lemonade_arcade.main - INFO - Returning model loading status: {'model_loaded': False, 'model_name': 'Qwen3-Coder-30B-A3B-Instruct-GGUF', 'current_model': None}
INFO:     127.0.0.1:42988 - "GET /api/model-loading-status HTTP/1.1" 200 OK
2025-08-26 15:07:13,639 - lemonade_arcade.main - INFO - Load model endpoint called
2025-08-26 15:07:13,639 - lemonade_arcade.main - INFO - Loading required model: Qwen3-Coder-30B-A3B-Instruct-GGUF
2025-08-26 15:07:13,671 - lemonade_arcade.main - ERROR - Failed to load model: HTTP 422
2025-08-26 15:07:13,671 - lemonade_arcade.main - INFO - Load model result: {'success': False, 'message': 'Failed to load model: HTTP 422'}
INFO:     127.0.0.1:42988 - "POST /api/load-model HTTP/1.1" 200 OK

[Ploux]

This was the result of a permission error when trying to create /usr/bin/vulkan directory. The lemonade-server was trying to install the Vulkan backend for llama.cpp but didn't have permission to write to /usr/bin/. I tried:

$ lemonade-server-dev serve --llamacpp cuda

But got:

usage:  serve [-h] [--port PORT] [--host HOST]
              [--log-level {critical,error,warning,info,debug,trace}]
              [--llamacpp {vulkan,rocm}] [--ctx-size CTX_SIZE]
 serve: error: argument --llamacpp: invalid choice: 'cuda' (choose from 'vulkan', 'rocm')

chocolate or strawberry, there is no vanilla :D

Fix

sudo mkdir -p /usr/bin/vulkan
sudo chown $USER:$USER /usr/bin/vulkan