The data mistakes that turn a migration into a nightmare

A warning worth reading twice,

The demo always looks fine. A handful of products slide across, the homepage renders, everyone relaxes. Then you migrate the full catalogue and the cracks appear, usually in the parts nobody thought to check.

Where data quietly goes wrong

Data migration fails in small, boring ways that add up to a bad launch.

• Variants collapse into single products, or the wrong way round
• Product images lose their order or their alt text
• Historic orders arrive without their line-item detail
• Customer accounts move but their saved addresses do not
• Metafields and custom attributes get silently dropped

None of these crash the site. That is exactly why they slip through.

Test with the messy stuff

When you check a migration, do not test your cleanest product. Test your worst one.

1. Pick your most complicated item with the most variants and options
2. Pick a customer with a long order history and multiple addresses
3. Pick a discontinued product that still needs its old URL to work
4. Compare old and new field by field, not at a glance

If your ugliest records survive the move intact, the tidy ones will look after themselves.

Clean before you carry

Here is the part people resist. A migration is your one good chance to leave the rubbish behind. Dead products, duplicate customers, half-finished draft pages. Do not carry them across out of habit.

Agree a cut-off. Decide what genuinely needs to come with you and what can stay archived in an export somewhere safe. A smaller, cleaner dataset moves faster, tests faster and costs less to get right.

The teams who suffer most are the ones who treat data as an afterthought and discover the gaps a week after go-live. Do the unglamorous checking early. If you would like a checklist tailored to your catalogue, request pricing and I will put one together with you.