Troubleshooting

prefixUrl rejects a leading slash

Use string OpenAPI paths with the fetcher client, not the raw ky instance. Fetcher retries known ky leading-slash prefixUrl errors by stripping the slash.

If you removed prefixUrl with extend({ prefixUrl: undefined }), use absolute URLs or paths accepted by ky.

Path parameter is missing

A template such as /users/{id} requires params.path.id on shortcut calls or path.id on callable calls.

api.get('/users/{id}', {
  params: { path: { id: '42' } },
});

Cookie parameters do not appear on the network

params.cookie is currently type-only at runtime. If you need a cookie header, set it explicitly through headers or rely on browser credential behavior.

My form upload has the wrong content type

Do not manually set Content-Type for multipart/form-data unless you are also controlling the boundary. Let the platform generate it from the FormData body.

I expected safe to return raw text

safe reads JSON and returns parsed data on success. For text, blob, stream, or custom body handling, use the default ky-style surface and read the response manually.