Updating product via admin console API breaks before:product.updated in certain conditions

[sebastian-meckovski]

Updating a product via PUT in the admin console API causes before:product.updated function to permanently stop firing for that product — but only when certain fields are updated.

Reproduction steps:

1. Create product with custom width and height attributes. (selection field, parsed as int)
2. Create and deploy function:

export const config: SwellConfig = {
  description: 'Auto-calculate product price from width/height attributes',
  model: {
    events: ['before:product.created', 'before:product.updated'],
    sequence: 1,
  },
};

const round2 = (n: number): number => Math.round(n * 100) / 100;

export default async function (req: SwellRequest) {
  const { data } = req;

  const width = parseFloat(data.attributes?.width);
  const height = parseFloat(data.attributes?.height);

  if (isNaN(width) || isNaN(height)) {
    console.log('No valid width/height attributes, skipping price calculation');
    return;
  }

  const eurPrice = round2(width * height * 0.1);
  const usdPrice = round2(width * height * 0.12);

  console.log(`Calculating price: EUR ${eurPrice}, USD ${usdPrice}`);

  return {
    price: eurPrice,
    currency: 'EUR',
    purchase_options: {
      standard: {
        active: true,
        price: eurPrice,
        $currency: {
          EUR: { price: eurPrice },
          USD: { price: usdPrice },
        },
      },
    },
    $currency: {
      EUR: { price: eurPrice },
      USD: { price: usdPrice },
    },
  };
}

3. Test function by updating width or height attributes - price updates immediately.
4. Update product name using PUT call in admin console

// PUT
{ "name": "Misty Mountains at Dawn" }

3. test function trigger by updating width or height attributes - should work as expected
4. Update product meta_title using PUT call in admin console

//PUT
{ "meta_title": "Misty Mountains at Dawn – BitBlocks Mosaic Wall Art" }

5. Getting 500 error Invalid character in header content ["Swell-Request-Log"] and after that product is broken beyond repair - After that, subsequent updates to the same product no longer trigger the function at all — no errors, no logs, complete silence. The only fix is to create a new product.

[dminch]

Thanks again for the clear reproduction, this nailed it for us. We were passing product data through an internal HTTP header that doesn't support special characters. The dash in your meta_title is what triggers it.

The reason the product appears permanently broken: once that character is stored on the product, the full record gets included in every subsequent function invocation, so it keeps failing. Removing the en dash from meta_title should restore function execution for that product.

The fix is in place. Pls, update cli and try it.