In rough order of frequency based on industry research:
1. Surprise costs at checkout
This is the #1 cause of abandonment globally — across every platform, every category, every store size. When a customer reaches checkout and sees costs they did not expect, abandonment spikes.
Common surprise costs:
- Shipping cost only revealed at checkout (most common).
- Sales tax appearing only after entering address.
- Currency conversion making the price look wildly different.
- Mandatory fees (handling, processing, etc.).
- "Free shipping over $X" threshold not communicated until cart.
Fix: show shipping cost and taxes earlier — on the cart page, even on product pages where possible. Display "Free shipping over $X" prominently throughout the storefront.
2. Forced account creation
Requiring customers to create an account before purchasing is one of the largest single conversion killers in ecommerce. Roughly 20-25% of customers abandon when forced to register.
Fix: enable guest checkout. Offer "save your details" after the order completes, not before. Open Settings, Checkout, Customer accounts, and set to "Optional" or "No accounts."
3. Slow load times (especially at checkout)
Every additional second of load time at checkout increases abandonment. Mobile-specifically: a checkout taking 4+ seconds on mobile loses customers who are otherwise ready to buy.
Fix: address site speed broadly — see Shopify Store Slow and Shopify Mobile Slow. For checkout-specific speed, third-party tax and shipping apps making blocking API calls during checkout are common culprits on Plus stores.
4. Missing express checkouts
Customers who reach checkout and do not see Shop Pay, Apple Pay, Google Pay, or PayPal are more likely to abandon. Express checkouts can lift checkout completion 5-15%.
Fix: enable all relevant wallets in Settings, Payments, Wallets. Shop Pay alone is one of the highest-impact toggles on a Shopify store.
5. Weak cart UX with no urgency or trust
When the cart page does not reinforce the buying decision, abandonment increases. Common weaknesses:
- No clear "next step" — just a cart page with a buried checkout button.
- No trust signals (return policy, secure checkout badges, guarantees).
- No urgency cues (low-stock indicators, shipping deadlines).
- Too many cross-sells distracting from completion.
- No estimated delivery date.
- Generic "cart" page with no brand personality.
Fix: cart page deserves the same conversion attention as the product page. Make the checkout CTA dominant, add trust signals, show delivery date, and limit upsells to 1-2 highly relevant ones.
6. Other meaningful causes (less common)
- Payment provider declining cards (see Shopify Payments Not Working).
- No shipping rates available (see Shopify Shipping Not Working).
- Address validation rejecting customers.
- 3D Secure (3DS) authentication failing silently.
- "Discount code" field appearing — customers leave to search for codes (and many do not return).
- Mobile checkout bugs from custom themes or theme customizations.