pip ResolutionImpossible: resolve conflicting requirements, not the download speed

Symptoms and scope

Dependency resolution failures mean pip could not satisfy the requested constraints. Separate a real conflict from slow backtracking, timeouts and certificate failures before retrying.

Error fragments for search; IDs, values and filenames may vary:

ResolutionImpossible
conflicting dependencies

Source-supported context

pip documents dependency resolution and conflicts. Ignoring dependencies does not make two non-overlapping version requirements compatible. Source 1 Source 2

Cases to distinguish

1. Two required node packages pin mutually incompatible dependency versions.

2. A manually added constraint unnecessarily narrows the available versions.

3. Lengthy resolver backtracking is mistaken for a stalled network connection.

Diagnostic sequence

The sequence below is an editorial procedure based on the cited context, not a diagnosis already confirmed for your environment.

Step 1. Save the exact conflicting requirements and the packages that introduced them. Check whether the failure is a resolver report or a transport error.

Step 2. Look for supported node versions with an overlapping dependency set, or remove an unneeded requirement in a copy of the environment.

Step 3. When both incompatible workflows are needed, use separate ComfyUI environments. Share model storage where appropriate, not their site-packages directories.

Step 4. Check declarations, imports and a minimal workflow, then record the resolved versions for recovery.

Completion check

The selected dependency set resolves and the required nodes run. Solver success alone does not prove that GPU extensions match the device.

Limitations and cautions

--no-deps or other ways to bypass resolution are not evidence that a conflict was fixed. Avoid replacing a failed dependency solution with an untracked pile of packages.

Original sources

• pip dependency resolution — original record checked 2026-09-21.
• pip check — original record checked 2026-09-21.

Localization prepared: 2026-09-22. The source-check dates above were inherited from the existing article; this translation does not claim they were all rechecked today. No GPU run, minimum-memory measurement or runtime guarantee is supplied.

Related troubleshooting and guides

• Install ComfyUI manually in an identifiable, recoverable Python environment
• NumPy ABI errors: _ARRAY_API and dtype size changed