Troubleshooting

First move, always: add mdyDevtools to the <mdy-form> and press Ctrl+Shift+D. The panel shows every field’s value, valid/touched/dirty/ pending and each error with its origin ([validation], [async], [cross-field], [server]).

Why is canSubmit() false?

canSubmit = !submitting && valid && !pending (in the default "valid-only" mode). In the devtools check, in order:

1. valid: false — filter “only invalid”: some field has errors, or a cross-field validator failed (form-level errors show on errorsFor("")).
2. pending: true — an async validator is still in its debounce+run window; canSubmit waits for it by design.
3. submitting: true — the previous submit’s promise never resolved. Check your action for a hanging request.
4. Mode is "manual" — canSubmit is always false there; drive submission yourself.

Why is a field still pending?

pending covers the whole debounce window plus the validator run. If it never settles: your async validator’s promise never resolves — pass timeoutMs to serverValidator()/upsertAsyncValidators() so the run aborts and settles with a kind: "async-timeout" error instead of hanging forever — or the value keeps changing (every change restarts debounce).

Why was a server error cleared?

Server errors are snapshotted against the submitted value and shown only while the field still holds that value — editing the field clears them (that is the contract). They also clear on reset() and are replaced wholesale by the next submit. An error whose path matches no registered field is not lost: it surfaces on errorsFor("").

Why was my draft not restored?

In order of likelihood:

1. The draft was cleared by a successful submit (by design).
2. ttlMs expired or version changed — both discard the stored draft.
3. The field is listed in exclude — excluded fields are never restored.
4. The form was pristine when it last closed — a pristine form writes no draft.
5. Storage unavailable (private mode, blocked cookies, SSR) — the default storage silently degrades to a no-op.

Why is a control not registered / its state empty?

• Typo in name (declarative mode creates a new field per unique name — a typo silently forks the state). Use typed [field] bindings to make this a compile error.
• Two controls share one name: both bind to the same state (dev-mode console warning). Rename one.
• The control sits outside the <mdy-form> element, so it found no registry — check the console for the dev-mode error.

Why did my value reset to null after setValue()?

setValue has replace semantics: fields absent from the passed object are reset to null. Use patch()/patchValue() to change a subset.

Why does getChanges() report an unchanged object field?

Leaves compare with Object.is (reference equality for objects/arrays). A re-created array/object counts as changed even if deep-equal. See the mental model.