Can a Shopify theme update break accessibility?

Yes. A theme update can replace repaired templates, change focus behavior, alter heading structure, or introduce new components with missing labels. The storefront may look unchanged while keyboard and screen reader behavior regresses. Run an accessibility scan in preview before publishing, then rescan the live store immediately after the update and compare it with the last clean baseline.

Why fixes disappear

Direct edits to an older theme version may not survive an upgrade. Even when code merges cleanly, new markup and JavaScript can change focus order or accessible names without producing a visual defect.

A safer release check

Test the preview theme across the purchase path, store the results, publish during a staffed window, and rerun the same routes live. A diff should identify only new failures so developers can tie each regression to the release.