# X_SET_COOKIE_HAND_BUILT

## Means

a `Set-Cookie` attribute is spelled in a literal, or a `Set-Cookie` header is written by name, outside `packages/core/src/cookie.ts` and `packages/http/src/set-cookie.ts`

## Typical cause

a header built by hand (`'Path=/; HttpOnly'`, `` `Max-Age=${s}` ``) — the bytes core's serializer would have refused or encoded go out as written, and two spellings of one header drift

## Fix

`setCookie` / `deleteCookie` from `@ultimat3/http`, or `serializeSetCookie` below http; then `bun run set-cookie-literals --json`

[CLI and verify](/error-codes#cli-and-verify)