Cannot read properties of null (reading 'useSyncExternalStore')

[jaspreet-singh-96]

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I don't know if this has happened to anyone else, but I am getting below error when running the app in prod.

TypeError: Cannot read properties of null (reading 'useSyncExternalStore')
at exports.useSyncExternalStore (/Users/jaspreetsingh/Projects/Web/buy2deal-v2/buy2deal/node_modules/.bun/react@19.2.5/node_modules/react/cjs/react.production.js:533:33)
at useStoreR19 (file:///Users/jaspreetsingh/Projects/Web/buy2deal-v2/buy2deal/apps/storefront/dist/server/_ssr/select-BRmrAfFK.mjs:4882:46)
at useStoreFast (file:///Users/jaspreetsingh/Projects/Web/buy2deal-v2/buy2deal/apps/storefront/dist/server/_ssr/select-BRmrAfFK.mjs:4926:24)
at useStore (file:///Users/jaspreetsingh/Projects/Web/buy2deal-v2/buy2deal/apps/storefront/dist/server/_ssr/select-BRmrAfFK.mjs:4872:9)
at DialogStore.useState (file:///Users/jaspreetsingh/Projects/Web/buy2deal-v2/buy2deal/apps/storefront/dist/server/_ssr/select-BRmrAfFK.mjs:5150:10)
at useSyncedFloatingRootContext (file:///Users/jaspreetsingh/Projects/Web/buy2deal-v2/buy2deal/apps/storefront/dist/server/_ssr/select-BRmrAfFK.mjs:5264:26)
at usePopupStore (file:///Users/jaspreetsingh/Projects/Web/buy2deal-v2/buy2deal/apps/storefront/dist/server/_ssr/select-BRmrAfFK.mjs:5322:2)
at DialogStore.useStore (file:///Users/jaspreetsingh/Projects/Web/buy2deal-v2/buy2deal/apps/storefront/dist/server/_ssr/DialogRoot-D61RgB2d.mjs:132:10)
at useRenderDialogRoot (file:///Users/jaspreetsingh/Projects/Web/buy2deal-v2/buy2deal/apps/storefront/dist/server/_ssr/DialogRoot-D61RgB2d.mjs:166:28)
at DialogRoot (file:///Users/jaspreetsingh/Projects/Web/buy2deal-v2/buy2deal/apps/storefront/dist/server/_ssr/DialogRoot-D61RgB2d.mjs:501:9)

I haven't noticed anything breaking, but this error keeps showing up in server console.

Tech Stack:
BaseUI: 1.6.0
Framework: Tanstack Start React 1.168.32 / Tanstack Router: 1.170.18
Build Tools: Vite 8.1.5 / Nitro 3.0.260610-beta

[michaldudak]

It's hard to tell for sure, but it looks like you might have multiple copies of React bundled in the server build, e.g. one chunk resolving the CJS build via node_modules/.bun/react@19.2.5/... (visible in the trace) while react-dom/server or another chunk resolves a different copy.

It could also be that React was accidentally bundled (not externalized) in the Vite SSR / Nitro output - if ssr.noExternal (or Nitro's rollup config) inlines React into one chunk while another imports it from node_modules, you get two instances even with a single installed version.

Another option is react / react-dom version mismatch: react-dom requires the exact same react version; a lockfile that resolves e.g. react@19.2.5 for the app but a different version for react-dom's peer produces the same symptom.