Shopify Help: 5 Checks When Checkout, Shipping or Theme Fails

Direct answer: when a Shopify store fails, I do not start from a fixed list of “common bugs”. I reproduce the issue and check market, shipping, payment, apps and theme in that order. The same symptom can have different causes and the correct fix is the one demonstrated by the real runtime.
1. Market and country
If a customer cannot buy from a country, I verify that the market and country are actually active for the store and compatible with the catalog and current settings. Looking at a single shipping rate is not enough.
2. Shipping
I check profiles, origins, affected products, rate conditions and mixed carts. Multiple profiles or locations can produce different combinations at checkout, so the test should use the same products and address that reproduce the error.
3. Payment
For a declined payment I distinguish gateway errors, missing requirements, payment-method configuration and provider responses. I do not automatically blame Shopify or the theme. I use available test modes and logs without creating real transactions when possible.
4. Apps and scripts
After installations, updates or removals I check app embeds, scripts and integrations that are actually loaded. I do not assume every uninstalled app leaves code behind, but I inspect the theme and console when the problem is consistent with a script or frontend dependency.
5. Theme and regression
If the problem appears after a change, I compare a theme copy, the affected file and behavior before and after. On Online Store 2.0 I also inspect JSON templates, sections and Theme Editor settings, not only theme.liquid.
When code changes are needed
I intervene only after isolating the cause. A fix should include desktop/mobile testing and regression checks on connected functions. “The site opens now” is not enough if cart, tracking or apps stop working.
These interventions are part of my Shopify support for Basic, Shopify and Advanced stores.
Updated September 3, 2026.

