Skip to content

Errors without a code

Errors without a code in the Diagnostics reference guide.

For agentsUpdated 2026-10-20

These messages have no SHADOW_ code. The text is stable enough to search for.

Message starts with	Where	Meaning and fix
`ShadowStore: the store is read-only`	`useStore` views	You assigned to a store outside `setStore((draft) => ...)`. Write through the setter.
`ShadowStore (...): a draft was used after its setStore() call returned`	`setStore` drafts	A draft proxy was kept and written to later. Drafts are valid only inside the update function.
`ShadowStore...: the key "__proto__" cannot be used in a path`	`setStore`	`__proto__`, `constructor` and `prototype` are reserved and never stored.
`addEventListener(): the handler must be a function`	`addEventListener`, compiled `on:`	The handler is not a function, `[fn, data]` tuple or object with `handleEvent`.
`insert(): a value contains itself`	`insert`, JSX children	An array that contains itself was inserted.
`ShadowJS Switch: children must be <Match>`	`Switch`	Only `Match` elements are allowed directly inside `Switch`.
`ShadowJS Dynamic: invalid tag`	`Dynamic`	The `component` string is not a plain tag name, or it is `script`.
`ShadowJS Show: stale accessor`	`Show` callback children	The accessor was read after the branch was replaced. Read it only while the condition is truthy.
`renderId must be made of letters, digits, _ and -`	`renderToString`, `renderToStringAsync`, `renderToStream`	The render id is written into markup, so it is restricted.
`ssr(): parts must have one more entry than there are holes`	`ssr`	Compiler output or hand-written call has the wrong shape.
`deserialize(): ...`	`deserialize`	The text is not output of `serialize`.
`ShadowJS head: ...`	`useHead`, `Title`, `Meta`, `Link`	Invalid tag description: unsupported tag, event attribute, reserved attribute, children on a void tag.