data too long for a QR code (${data.length} bytes, EC ${ecLe

Error message

data too long for a QR code (${data.length} bytes, EC ${ecLevel})

What it means

encodeBytes walks QR versions up to maxVersion looking for one whose data capacity fits the payload; if even the maximum version with the chosen error-correction level cannot hold the bytes, it throws a descriptive length error.

Source

Thrown at packages/coding-agent/src/utils/qrcode.ts:196

	/** Encode a string in byte mode (UTF-8). Throws if it exceeds version 40. */
	static encodeText(text: string, ecLevel: QrEcLevel = "M", options?: QrEncodeOptions): QrCode {
		return QrCode.encodeBytes(new TextEncoder().encode(text), ecLevel, options);
	}

	/** Encode raw bytes in byte mode. Throws if they exceed version 40 at this EC level. */
	static encodeBytes(data: Uint8Array, ecLevel: QrEcLevel = "M", options?: QrEncodeOptions): QrCode {
		const ec = EC_LEVELS[ecLevel];
		const minVersion = Math.max(MIN_VERSION, options?.minVersion ?? MIN_VERSION);
		const maxVersion = Math.min(MAX_VERSION, options?.maxVersion ?? MAX_VERSION);

		let version = minVersion;
		for (; ; version++) {
			const capacityBits = dataCodewords(version, ec.table) * 8;
			const usedBits = 4 + charCountBits(version) + data.length * 8;
			if (usedBits <= capacityBits) break;
			if (version >= maxVersion) {
				throw new Error(`data too long for a QR code (${data.length} bytes, EC ${ecLevel})`);
			}
		}

		const bits = new BitBuffer();
		bits.append(BYTE_MODE_INDICATOR, 4);
		bits.append(data.length, charCountBits(version));
		for (const b of data) bits.append(b, 8);

		const capacityBits = dataCodewords(version, ec.table) * 8;
		bits.append(0, Math.min(4, capacityBits - bits.length)); // terminator
		bits.append(0, (8 - (bits.length % 8)) % 8); // byte-align
		for (let pad = 0; bits.length < capacityBits; pad ^= 1) bits.append(PAD_BYTES[pad]!, 8);

		const codewords = QrCode.#interleave(bits.toBytes(), version, ec.table);
		const mask = options?.mask ?? -1;
		if (mask < -1 || mask > 7) throw new Error(`invalid mask ${mask}`);
		return new QrCode(version, ecLevel, codewords, mask);
	}

View on GitHub (pinned to 9690622007)

Solutions

Shorten the payload (URL shortener, trim fields, drop optional data).
Lower the error-correction level (H to Q to M to L) to gain capacity.
Split the data across multiple QR codes or use a different transport.
If the library exposes it, increase maxVersion — otherwise the data physically cannot fit one QR code.

Example fix

// before: encodeBytes(longVCard, { ecLevel: "H" }); // 2KB payload  // after: shorten the payload (or use ecLevel "L"), then encodeBytes(shortened, { ecLevel: "L" });

Defensive patterns

Strategy: validation

Validate before calling

const MAX_BYTES = { L: 2953, M: 2331, Q: 1663, H: 1273 } as const; if (payload.length > MAX_BYTES[ecLevel]) throw new Error(`payload too long for QR at EC ${ecLevel}`);

Try / catch

try { const qr = encodeBytes(data, { ecLevel }); } catch (err) { if (err instanceof Error && err.message.startsWith("data too long")) { return encodeBytes(shorten(data), { ecLevel: "L" }); } throw err; }

Prevention

Cap payloads well under ~1.2KB; prefer linking to content over embedding it.
Use URL shorteners for long links destined for QR codes.
Choose the lowest EC level your use case tolerates for maximum capacity.
Split very large data across multiple codes rather than forcing one code.

When it happens

Trigger: Calling the QR encoder (encodeBytes) with data longer than the maximum QR version's byte capacity at the given EC level — e.g. more than ~1,273 bytes at EC H, or ~2,953 bytes at EC L in byte mode.

Common situations: Encoding long URLs with huge query strings, vCards with many fields, Wi-Fi payloads with long keys, or embedding a file/blob into a QR code.

Related errors

AI-assisted analysis of can1357/oh-my-pi@9690622007 (2026-08-31). Data as JSON: /api/errors/3dcc41b163a17ab5. Report an issue: GitHub.