Missing safetensors package or unreadable weights? Diagnose them separately

A file extension is not a Python installation

Safetensors documents a Python package and file-reading interfaces. An import failure occurs before a particular weight file can be parsed. A later SafetensorError reports a read or format problem, but its class name alone does not prove download corruption: upstream also has distinct invalid-header, size-limit, offset and incomplete-buffer errors. Safetensors docs Reader error definitions

python -c "import sys; print(sys.executable); import safetensors; print(safetensors.__version__)"

Run that command with the Python interpreter used to start ComfyUI; an installed package in another interpreter does not resolve the active import. If import succeeds, preserve the exact exception and failing path. For a file-reading error, record repository, revision, path, actual byte size and any publisher-provided integrity value before deciding whether the download is incomplete, the file format is unsupported, or the selected file is wrong. A model family name alone is not a file identity.

Our recommended replacement procedure preserves the original: download a separate candidate, compare it, then decide whether to replace the active file. Do not rename a suffix or alter a header to suppress validation errors.

Record library import, standalone file reading and workflow loading as separate checks. The documented safetensors.torch.load_file reads tensors from a named file; reading successfully does not establish that its keys or architecture fit a ComfyUI loader. Torch API A locally computed hash can compare two local copies; it verifies publisher identity only when compared with a trusted publisher value.

Related checks

• Spandrel is installed but the model will not load: check architecture support
• Transformers errors: separate imports, API changes and model downloads

Sources and English text reviewed 2026-09-26. No package installation, local file read, ComfyUI run or GPU reproduction. Steps are editorial guidance, not a diagnosis of your file.