System
- LTX Desktop 1.2.7
- macOS Sonoma 14.8.2
- Mac Studio M2 Ultra
- 64 GB unified memory
Problem
Local generation fails every time.
The issue affects BOTH:
- Text-to-Image
- Image-to-Video
Generation always ends with:
HTTP 500
Caught an unknown exception
This happens with very simple prompts as well (for example: "A red apple on a wooden table"), so it does not appear to be prompt-related.
Models
Installation completed successfully.
Downloaded models include:
- LTX 2.5 distilled transformer
- Gemma4 text encoder
- Audio VAE
- Conv Video VAE
- Spatial upscaler
- Z-Image Turbo
Memory
This is NOT an out-of-memory issue.
Heartbeat reports approximately:
torch = 1.02 GiB
driver = 2.99 GiB
max = 48.00 GiB
Relevant backend log
The backend consistently crashes inside Apple's MPS attention backend:
mps_sdpa
mpsgraph_zc
followed by:
RuntimeError: Caught an unknown exception
Changing
"use_local_text_encoder": true
does not change the behaviour.
Attached
- complete backend session log
System
Problem
Local generation fails every time.
The issue affects BOTH:
Generation always ends with:
HTTP 500
Caught an unknown exception
This happens with very simple prompts as well (for example: "A red apple on a wooden table"), so it does not appear to be prompt-related.
Models
Installation completed successfully.
Downloaded models include:
Memory
This is NOT an out-of-memory issue.
Heartbeat reports approximately:
torch = 1.02 GiB
driver = 2.99 GiB
max = 48.00 GiB
Relevant backend log
The backend consistently crashes inside Apple's MPS attention backend:
mps_sdpa
mpsgraph_zc
followed by:
RuntimeError: Caught an unknown exception
Changing
"use_local_text_encoder": true
does not change the behaviour.
Attached