Pasted an error and just want it fixed? Pick the message you hit. Every page has the cause, the concrete fix, and — when it's a VRAM ceiling — the cheapest GPU that actually holds the model.
A "CUDA out of memory" error means the model needed more GPU VRAM than the card has. It is almost always a VRAM ceiling, not a bug in your workflow — the same graph runs fine on a bigger GPU.
ComfyUI couldn't find the checkpoint/LoRA the workflow references. The filename in the graph doesn't match any file in the models directory — often an exact-name or subfolder mismatch.
A ModuleNotFoundError at ComfyUI startup almost always means a custom node's Python dependency didn't install — the node folder is there, but a package it imports is missing.
Unable to establish network connection.
The GPU encountered a driver or runtime error.
The process was killed, likely due to memory limits.
The operation was blocked due to insufficient permissions.
The operation took too long to complete.
This is a container DISK limit, not VRAM. Model weights download to the container disk, and large checkpoints (a 62GB LTX-2 or 31GB Z-Image) overflow a small volume before the download finishes.
The workflow configuration is invalid.
A 401 on a model download means the weights are gated on HuggingFace (FLUX.1-dev, some Llama/Gemma repos) and the download had no accepted-license token. The node isn't missing — the download is being refused.
An API request failed with an error response.
Catch errors before they happen
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