@sentry/tanstackstart-react 10.55.0 regression: client SDK breaks React re-rendering in production builds (Mantine AppShell stuck)

[alex-zwingli]

Summary

Upgrading from @sentry/tanstackstart-react 10.54.0 → 10.55.0 causes a React component to stop re-rendering in response to state changes — but only in a production (minified) build. The dev server and a --mode development build are both unaffected. Bisected to the 10.55.0 release.

In our app it manifests on a Mantine AppShell: the mobile navbar (navbar.collapsed.mobile, driven by a useDisclosure/useState toggle in the header) stops updating. Clicking the hamburger flips the <Burger> to its open icon — so the state did change and that component re-rendered — but the AppShell's collapse <style> (which is derived from the same mobileOpened state via collapsed={{ mobile: !mobileOpened }}) never updates, so the navbar stays at transform: translateX(-100%) and the sidebar never slides in. Effectively the AppShell subtree stops reconciling on a state change that a sibling in the same parent component reacts to correctly.

SDK / environment

• @sentry/tanstackstart-react (+ transitive @sentry/react, @sentry/browser, @sentry/core)
• React 19.2.0
• @tanstack/react-start 1.139.x (Vite + Nitro)
• @mantine/core 8.3.10
• babel-plugin-react-compiler is enabled — but disabling it does not fix the bug.
• Build: vite build (production). Reproduces whether or not Sentry.init() actually runs — it breaks even when the client SDK is only imported but not initialized (no DSN), which suggests module-level/build behavior rather than a runtime integration.

Version bisection (production builds, identical app code)

@sentry/* version	Result
10.27, 10.40, 10.50, 10.52, 10.54.0	✅ works
10.55.0, 10.59.0, 10.60.0	❌ broken

The regression was introduced in 10.55.0 (each version built with a clean dependency install).

Suspected cause

The 10.55.0 changelog includes feat(tanstackstart-react): Enable component tracking (#21149), which is the most likely candidate for a change that alters how React components are tracked/reconciled. (I have not confirmed the exact mechanism.) Other 10.55 tanstackstart-react changes touching the client/hydration path: #21144 (distributed tracing — connects server↔client traces through hydration) and #21161 (move init to client entry).

What I ruled out

• Not our Sentry.init() config — reproduces even when the SDK is imported but never initialized (no DSN).
• Not the sentryTanstackStart Vite plugin — removing it from the build still reproduces.
• Not the React Compiler — disabling babel-plugin-react-compiler still reproduces.
• Not a hydration mismatch — a benign React Why can't I catch an error directly after install() ? #418 is present on the working 10.54 build too, so it is not the trigger.

Expected vs. actual

• Expected: importing/using the Sentry SDK does not change React's reconciliation; components re-render on state changes in a production build exactly as they do in dev.
• Actual: with 10.55.0+, a Mantine AppShell stops re-rendering on state changes in production builds, while a sibling component (the Burger) driven by the same state still updates.

Workaround

Pinning @sentry/* to 10.54.0 resolves it.

Reproduction

I don't yet have a trimmed-down standalone reproduction — the bisection was done against a large app. I'm happy to put together a minimal Vite + React 19 + Mantine AppShell + @sentry/tanstackstart-react repro if that would help narrow it down; just let me know. Given the SDK is in beta and the precise version bisection points at 10.55.0 (#21149), I wanted to file this early.

[linear-code]

JS-2861

[JPeer264]

Hey thanks a lot for helping us to improve our TanstackStart SDK. I just tried to reproduce it and set up a minimal app with Mantine and its AppShell, but couldn't reproduce it - the app always built successfully. However, it failed with a different error (even with a older version) when having our vite plugin with the combination of the nitro/vite plugin.

Do you have any specific Vite plugins that might cause this? Could you disable the Sentry TanStack Start Vite plugin and try again (or at least set it to sentryTanstackStart({ autoInstrumentMiddleware: false })? It was be really good if you have any leads or a minimal reproduction.

[getsantry]

This issue has gone three weeks without activity. In another week, I will close it.

But! If you comment or otherwise update it, I will reset the clock, and if you remove the label Waiting for: Community, I will leave it alone ... forever!

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"A weed is but an unloved flower." ― Ella Wheeler Wilcox 🥀