n8n-io/n8n · error · NodeOperationError

Unsupported mime type: ${mimeType} for selected loader: ${se

Error message

Unsupported mime type: ${mimeType} for selected loader: ${selectedLoader}

What it means

Error "Unsupported mime type: ${mimeType} for selected loader: ${selectedLoader}" thrown in n8n-io/n8n.

Source

Thrown at packages/@n8n/ai-utilities/src/utils/n8n-binary-loader.ts:79

				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}`,
			);
		}
	}

	private async getFilePathOrBlob(
		binaryData: IBinaryData,
		mimeType: string,
	): Promise<string | Blob> {
		if (binaryData.id) {
			const binaryBuffer = await this.context.helpers.binaryToBuffer(
				await this.context.helpers.getBinaryStream(binaryData.id),
			);
			return new Blob([binaryBuffer as BlobPart], {
				type: mimeType,
			});
		} else {

View on GitHub (pinned to 5ac6606e81)

When it happens

Trigger: Thrown at packages/@n8n/ai-utilities/src/utils/n8n-binary-loader.ts:79 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/057ac9f0397ec0b9. Report an issue: GitHub.