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webcolors is installed but CSS3_HEX_TO_NAMES is missing: check API changes

An AttributeError in a color node may concern an old mapping, not a missing module. Identify the exception before choosing a package repair.

Scope and symptoms

An AttributeError in a color node may concern an old mapping, not a missing module. Identify the exception before choosing a package repair.

Search fragments; wording and context vary:

No module named 'webcolors'
CSS3_HEX_TO_NAMES

Source-supported context

The webcolors changelog records removal of publicly exposed raw mappings in 24.6.0 and introduction of names() in 24.8.0. These are version-specific API changes, not a guarantee that an old node can use the newer interface unchanged. V04-WEBCOLORS

Distinguish these cases

1. The complete module is missing from the intended interpreter.

2. Import succeeds while a node accesses a no-longer-public mapping or unsupported internal path.

3. A supported conversion function rejects the color representation or specification supplied by the node.

Suggested diagnostic sequence

This sequence is editorial guidance, not a diagnosis of your machine.

1. Record the missing attribute and both node and library versions. Distinguish ModuleNotFoundError, AttributeError and an invalid-value conversion.

2. Prefer an author-maintained node update that uses documented public APIs. Test it in a copy before changing the working installation; do not edit installed dependency internals blindly.

3. If a legacy node must remain, create an isolated environment using its documented compatible combination. Do not apply an arbitrary downgrade to every node because an old forum post used it.

4. Test a known color and an unsupported input through the actual node, then check the dependency environment for new conflicts.

Completion checks

The failing attribute access is resolved, known colors convert correctly and invalid inputs produce understandable errors. Import alone is not an API compatibility check.

Limits and cautions

A new function is not necessarily a drop-in replacement for every dictionary use. Reverse mappings, aliases and color specifications still need consumer-specific handling; no untested source patch is supplied here.

Source review: 2026-09-22. No installation, GPU inference or user-environment repair was executed.

Original sources

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Check the next possible cause

The same symptom can come from a different cause. Work through these related entries in order.

  1. ModuleNotFoundError in ComfyUI even though the package is installedModuleNotFoundErrorA successful installation in a terminal does not show that ComfyUI uses the same Python. Separate the import name, distribution name and running interpreter before changing dependencies.
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Sources & references

Source-based editorial draft; no runtime verification. Version observations are scoped, and unknown wrapper identity is explicit.

01webcolors changelogSource checked: 2026-09-22

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