Troubleshooting

Problem	Likely cause	Fix
Missing container	querySelector returned null.	Check the selector and mount after the element exists.
Missing transport	mountForm needs a submit path.	Pass transport.
Invalid transport config	transport.submit is missing or invalid.	Pass an object with an async submit(request) method.
Backend response cannot be read	The application adapter parsed the wrong shape.	Fix the adapter parser and return the expected report contract.
Unknown field kind	Registry does not include the field.	Use built-ins or register a custom field.
Unknown report kind	Registry does not include the report.	Use classifier, regressor, or register a custom report.
Duplicate id	Two fields or reports share an explicit id.	Give each item a stable unique id.
Custom element name invalid	Custom renderer tag lacks a hyphen.	Use a valid custom element name such as risk-band-field.
Form not updating after remount	Host reused stale schema/state.	Keep schema creation intentional and unmount on route changes.
Styles not inherited	Design system uses its own mode.	Use mode: "inherit" or override tokens at the container.

Start with the browser console and the network tab. Most integration failures are either schema validation, missing DOM container, or backend response shape.