Custom validation failed: read the node's own error details

The generic banner says the node's validation rejected an input or raised an exception. It does not identify whether the real cause is a missing file, invalid media or code incompatibility.

Updated 2026-09-24Published revision: 4Source baseline: not recorded

Symptoms and scope

The generic banner says the node's validation rejected an input or raised an exception. It does not identify whether the real cause is a missing file, invalid media or code incompatibility.

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

Custom validation failed for node
custom_validation_failed
exception_during_validation

Source-supported context

Core validation invokes node-specific checks and includes returned details. An exception inside validation differs from an error during later GPU execution. Source 1 Source 2

Cases to distinguish

1. A node deliberately rejects an unavailable resource or unsupported input combination.

2. Its validation code is incompatible with the current core interface.

3. An environment/resource error inside validation is wrapped by the generic message.

Diagnostic sequence

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

Step 1. Expand details and traceback, retaining input_name, class and the complete custom message.

Step 2. Check the specific field or resource and the author's input requirements.

Step 3. Compare the node's minimal original example. Consider version/environment conflicts if even documented valid input fails.

Step 4. Report the minimal reproduction to that node's project with core and extension versions. Do not delete its validator to bypass the refusal.

Completion check

The node accepts the input and then executes successfully. Suppressing the validator does not establish that the data is correct.

Limitations and cautions

Validation can protect file, parameter and remote-interface constraints. Bypassing it may replace a clear early error with a harder runtime failure.

Original sources

ComfyUI execution.py validation — original record checked 2026-09-21.
ComfyUI custom node troubleshooting — 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.

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Sources & references

Localized from the existing Chinese research draft. Original source-check dates are retained; this translation is not new technical verification or a runtime test.

01ComfyUI execution.py validationSource checked: 2026-09-21 02ComfyUI custom node troubleshootingSource checked: 2026-09-21