solid-errors-reactivity-debugging

Quick Reference

Symptom	Cause	Fix
UI never updates after signal change	Signal getter not called in JSX: `{count}` instead of `{count()}`	ALWAYS call the getter: `{count()}`
Effect runs once, never again	Signal accessed outside tracking scope (component body, event handler)	Move signal access inside `createEffect` or JSX expression
Effect ignores some signals	Conditional access / early return before signal read	Read ALL signals before any conditional logic
Store property not updating in UI	Destructured store property: `const { name } = store`	ALWAYS access via `store.name` in JSX
Store update has no effect	Direct mutation: `store.name = "x"`	ALWAYS use `setStore("name", "x")`
Props stop updating	Destructured props: `function Comp({ name })`	ALWAYS use `props.name`, use `splitProps` if needed
Value is stale in timeout/callback	Signal value captured: `const v = count()` then used later	Call `count()` at the point where you need the value
Effect works initially but stops	`await` inside effect breaks synchronous tracking	Move async code to a separate function; read signals before `await`
Memo returns stale value	Memo dependency was untracked or destructured	Verify all signal getters are called inside memo callback
Store array update not reflected	Used `store.items.push()` instead of setter	Use `setStore("items", items.length, newItem)` or `produce`