n8n-io/n8n · error · NodeOperationError

Mime type doesn't match selected loader. Please select under

Error message

Mime type doesn't match selected loader. Please select under "Loader Type": ${neededLoader}

What it means

Error "Mime type doesn't match selected loader. Please select under "Loader Type": ${neededLoader}" thrown in n8n-io/n8n.

Source

Thrown at packages/@n8n/ai-utilities/src/utils/n8n-binary-loader.ts:64

			const processedDocuments = await this.processItem(items[itemIndex], itemIndex);

			docs.push(...processedDocuments);
		}

		return docs;
	}

	private async validateMimeType(
		mimeType: string,
		selectedLoader: keyof typeof SUPPORTED_MIME_TYPES,
	): Promise<void> {
		// Check if loader matches the mime-type of the data
		if (selectedLoader !== 'auto' && !SUPPORTED_MIME_TYPES[selectedLoader].includes(mimeType)) {
			const neededLoader = Object.keys(SUPPORTED_MIME_TYPES).find((loader) =>
				SUPPORTED_MIME_TYPES[loader as keyof typeof SUPPORTED_MIME_TYPES].includes(mimeType),
			);

			throw new NodeOperationError(
				this.context.getNode(),
				`Mime type doesn't match selected loader. Please select under "Loader Type": ${neededLoader}`,
			);
		}

		if (!Object.values(SUPPORTED_MIME_TYPES).flat().includes(mimeType)) {
			throw new NodeOperationError(this.context.getNode(), `Unsupported mime type: ${mimeType}`);
		}

		if (
			!SUPPORTED_MIME_TYPES[selectedLoader].includes(mimeType) &&
			selectedLoader !== 'textLoader' &&
			selectedLoader !== 'auto'
		) {
			throw new NodeOperationError(
				this.context.getNode(),
				`Unsupported mime type: ${mimeType} for selected loader: ${selectedLoader}`,
			);

View on GitHub (pinned to 5ac6606e81)

When it happens

Trigger: Thrown at packages/@n8n/ai-utilities/src/utils/n8n-binary-loader.ts:64 when the library encounters an invalid state.

Common situations: See trigger scenarios.

AI-assisted analysis of n8n-io/n8n@5ac6606e81 (2026-08-12). Data as JSON: /api/errors/f3c5ec00bc0bb0a4. Report an issue: GitHub.