n8n-io/n8n · error · NodeOperationError

The file "${fileName}" is ${sizeInMb} MB, which exceeds the

Error message

The file "${fileName}" is ${sizeInMb} MB, which exceeds the ${limitInMb} MB limit for passing binary data to the model

What it means

Thrown by addPassthroughBinary (Tools Agent common.ts) when a binary item being passed through to the model exceeds the configured size cap. The limit defaults to DEFAULT_MAX_PASSTHROUGH_BINARY_SIZE_BYTES and is overridable via the AiConfig.maxAgentPassthroughBinarySizeBytes field, which in turn reads N8N_AI_AGENT_MAX_PASSTHROUGH_BINARY_SIZE_BYTES. The check uses Buffer.byteLength on the decoded base64 to measure true size, and the error message reports both the file size and the limit in MB.

Source

Thrown at packages/@n8n/nodes-langchain/nodes/agents/Agent/agents/ToolsAgent/common.ts:164

		base64Data = Buffer.from(binaryBuffer).toString(BINARY_ENCODING);
	} else {
		base64Data = data.data.includes('base64,') ? data.data.split('base64,')[1] : data.data;
	}

	// Guard against oversized attachments. Providers that accept inline (base64)
	// documents cap the request payload, so we reject early with a clear message
	// instead of surfacing an opaque provider-side error. The limit is
	// configurable via N8N_AI_AGENT_MAX_PASSTHROUGH_BINARY_SIZE_BYTES.
	const maxSizeInBytes =
		Container.get(AiConfig)?.maxAgentPassthroughBinarySizeBytes ??
		DEFAULT_MAX_PASSTHROUGH_BINARY_SIZE_BYTES;
	// Decode the base64 length exactly (Buffer.byteLength accounts for padding).
	const sizeInBytes = Buffer.byteLength(base64Data, 'base64');
	if (sizeInBytes > maxSizeInBytes) {
		const fileName = data.fileName ?? 'binary file';
		const sizeInMb = (sizeInBytes / (1024 * 1024)).toFixed(1);
		const limitInMb = (maxSizeInBytes / (1024 * 1024)).toFixed(1);
		throw new NodeOperationError(
			ctx.getNode(),
			`The file "${fileName}" is ${sizeInMb} MB, which exceeds the ${limitInMb} MB limit for passing binary data to the model`,
			{
				description:
					'Reduce the file size, or disable the binary passthrough option for this input.',
			},
		);
	}

	// PDFs (and other documents) are passed as a file content block. OpenAI's
	// Responses API needs its native `input_file` part; every other supported
	// provider consumes the LangChain standard data content block.
	if (type === 'file') {
		if (contentFormat === 'openai-responses') {
			return {
				type: 'input_file',
				file_data: `data:${data.mimeType};base64,${base64Data}`,
				filename: data.fileName ?? 'attachment.pdf',

View on GitHub (pinned to 5ac6606e81)

Solutions

1. Reduce the input file size before it reaches the agent (compress the image, split the PDF, or downscale).
2. Disable the 'passthroughBinaryImages' / 'passthroughBinaryPdfs' option if binary passthrough is not required.
3. Raise the limit by setting N8N_AI_AGENT_MAX_PASSTHROUGH_BINARY_SIZE_BYTES in the environment (self-hosted only), mindful of provider payload limits.

Example fix

// before — oversized binary reaches the agent and trips the guard

// after — gate passthrough by size upstream
const MAX = 20 * 1024 * 1024;
const items = [];
for (const item of $input.all()) {
  const b = item.binary?.data;
  if (b && Buffer.from(b.data, 'base64').length > MAX) {
    // drop binary, keep text only
    const { data, ...rest } = item;
    items.push({ json: item.json, binary: undefined });
  } else {
    items.push(item);
  }
}
return items;

const limit = Container.get(AiConfig)?.maxAgentPassthroughBinarySizeBytes ?? DEFAULT_MAX_PASSTHROUGH_BINARY_SIZE_BYTES;
for (const item of items) {
  for (const key of Object.keys(item.binary ?? {})) {
    const b = item.binary[key];
    const buf = b.id ? await ctx.helpers.binaryToBuffer(await ctx.helpers.getBinaryStream(b.id)) : Buffer.from(b.data, 'base64');
    if (buf.length > limit) {
      throw new NodeOperationError(ctx.getNode(), `Binary '${key}' (${(buf.length/1048576).toFixed(1)} MB) exceeds the ${(limit/1048576).toFixed(1)} MB passthrough limit.`);
    }
  }
}

function isWithinBinaryLimit(buf: Buffer, limit: number): boolean {
  return buf.length <= limit;
}

When it happens

Trigger: passthroughBinaryImages or passthroughBinaryPdfs is enabled on the Agent, and an incoming item carries a binary file (image/PDF) whose decoded size exceeds the configured limit. The model would otherwise receive an oversized payload and the provider would reject it opaquely.

Common situations: Large PDF or high-res image attached to the trigger; default limit too low for the use case; user enabled binary passthrough without sizing the inputs.

Related errors

• No binary data found, please connect a binary to the input i
• No binary data received.
• Please connect a model to the Fallback Model input or disabl
• Please connect a model to the Fallback Model input or disabl
• Tools Agent requires Chat Model which supports Tools calling

AI-assisted analysis of n8n-io/n8n@5ac6606e81 (2026-08-12). Data as JSON: /api/errors/07d836926733d769. Report an issue: GitHub.