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Checkout Issues

Having problems completing checkout with bundles? Here's how to diagnose and fix common checkout issues.

Updated yesterday

Common Checkout Problems

  1. Error messages at checkout

  2. Bundle items disappear at checkout

  3. Discount not applied at checkout

  4. "Item unavailable" errors

  5. Payment fails with bundle

Error: "This product is not available"

This usually means an item in the bundle is out of stock or can't ship to the customer's location.

Causes:

  • Product went out of stock between cart and checkout

  • Product can't ship to the customer's address (multi-location inventory)

  • Variant is no longer available

Solutions:

  1. Check inventory:
    Go to Products in Shopify admin Find the item mentioned in the error Verify it has inventory

  2. Multi-location stores:
    Enable Fulfillable Inventory (see Multi-Location Inventory) This prevents customers from adding items that can't ship to them

  3. Have customer refresh cart:
    Remove the bundle from cart Go back to the bundle page Add items again

Error: "Cart has been modified"

Shopify shows this when something changed between adding items and checkout.

Causes:

  • Product price changed

  • Inventory changed

  • Bundle configuration updated

Solution: Have the customer refresh their cart and try again. If they continue to see this error:

  1. Clear cart completely

  2. Return to bundle product page

  3. Add bundle items fresh

  4. Proceed to checkout immediately

Bundle Items Missing at Checkout

If items disappear between cart and checkout:

Check 1: Items are bundle items

Bundle items must be added through the bundle interface, not individually. Items added separately won't have the bundle metadata and may behave differently.

Check 2: Cart Transform is working

The Cart Transform processes bundle items at checkout. If it's not running:

  1. Open MOD Bundles app

  2. Try creating a simple test bundle

  3. This can reinstall the Cart Transform function

Check 3: Test in incognito

Browser extensions or cached data can interfere:

  1. Open incognito/private window

  2. Add bundle to cart

  3. Proceed to checkout

  4. Check if items appear

Discount Not Applied at Checkout

If you see full prices at checkout instead of bundle prices:

This is usually a Cart Transform issue:

  1. Verify discount is set:
    Open your bundle in MOD Bundles Confirm a discount type is selected Save and try again

  2. Check Cart Transform status:
    Go to Settings → Apps and sales channels Find MOD Bundles Verify it has cart/checkout access

  3. Test with a new bundle:
    Create a simple test bundle with obvious discount If that works, the original bundle may need reconfiguration

See also: Discount Not Applying

Payment Processing Fails

If payment fails specifically with bundles in cart:

Check 1: Is it bundle-specific?

Test if the same products work when purchased individually (not as a bundle). If yes, the issue is bundle-related.

Check 2: Price calculation

Sometimes extreme discounts or unusual pricing can cause payment issues:

  • Very small total amounts (under $1)

  • $0 totals from 100% discounts

  • Currency conversion edge cases

Check 3: Payment provider limits

Some payment providers have restrictions. Check with your payment provider if:

  • Order total is unusually high or low

  • Multiple line items exceed limits

  • Special characters in product names cause issues

Checkout Extensibility Errors

MOD Bundles requires Shopify's checkout extensibility. If you see errors related to this:

Requirements:

  • Shopify Basic plan or higher

  • Not available on Starter/Lite plans

  • Checkout extensibility must be enabled

If you recently changed plans:

  1. Verify your plan includes checkout extensibility

  2. You may need to contact Shopify to enable it

  3. Wait a few hours for changes to take effect

Order Shows Wrong Items

If the completed order shows different items than expected:

Check the order details:

  1. Go to Orders in Shopify admin

  2. Find the order

  3. Look at line items

Bundle items should appear as individual line items with:

  • The actual product names

  • Bundle identifier in properties

  • Discounted prices (if applicable)

If items are wrong:

  • The bundle configuration may have changed

  • Check your bundle settings match what you expect

Slow Checkout with Bundles

If checkout is noticeably slower with bundles:

This can happen when:

  • Bundle has many items (10+ products)

  • Products have many variants

  • Multiple bundles in cart

Solutions:

  • Simplify bundles where possible

  • Reduce number of variants if not needed

  • Contact support if checkout takes more than 10 seconds

Testing Checkout

To isolate bundle checkout issues:

  1. Test with minimal bundle:
    Create a 2-product bundle Simple discount (like 10% off) Add to cart and checkout

  2. Test different payment methods:
    Try Shopify Payments (if available) Try PayPal or other providers Use test mode if possible

  3. Test different scenarios:
    Single bundle Bundle + regular product Multiple bundles

Still Having Issues?

If checkout problems persist:

  1. Document the error:
    Screenshot the exact error message Note the URL where it happens Record what steps led to the error

  2. Check Shopify status:
    Visit status.shopify.com Checkout issues can sometimes be platform-wide

  3. Contact support:
    Share error screenshots Include order numbers if available Describe which bundles are affected

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