[LukasTy]

Drop React 17 support in v10. React 18 is the new minimum. This PR is for discussion: master still ships v9, so it stays a draft until v10 starts. v9 stays the line for React 17 users.

Closes #17637. Follow-up to #24038, which fixed six React 17 crashes in v9.17.0.

Why

• CI tests only React 18 and 19. The unit suite cannot run on React 17: all test files fail at import.
• React 17 is about 1.6% of the weekly react downloads.
• All axis charts crashed on React 17 from v9.6.0 for 4 months. Nobody reported it.

Wins

• Diff: 121 files changed, 272 insertions, 433 deletions (net -161 lines). Without pnpm-lock.yaml and whitespace: 208 insertions, 325 deletions.
• Dependencies: use-sync-external-store removed from 4 packages (x-charts, x-chat-headless, x-data-grid, x-scheduler-internals). @types/use-sync-external-store removed from 7 packages. 2 catalog entries removed. The lockfile loses 46 lines.
• Shim: 5 use-sync-external-store/shim imports (4 imports and 1 re-export from @mui/x-data-grid/internals) and 6 hook calls now use React.useSyncExternalStore.
• useId: 98 calls in 71 files now use React.useId() instead of the @mui/utils/useId and @base-ui/utils/useId wrappers. 71 wrapper imports removed. The IDs do not change: on React 18+, both wrappers return React.useId() as is.
• React 17 first-render guards: 24 removed. That is 2 runtime guards (ScatterPlot progressive plan, GridActionsCell menu button), 8 string | undefined types, 13 ! assertions and 1 ?? '' fallback.
• PropTypes: 2 props of GridHeaderFilterMenu are required again (revert of [DataGridPro] Avoid proptypes warnings with header filters in React 17 #17482).
• ESLint: the React 17 guard from [charts][chat][DataGridPremium][scheduler] Fix React 17 crashes #24038 (12 restricted React.* properties) becomes a React 18 guard (6 properties: use, useActionState, useOptimistic, useEffectEvent, Activity, cache).
• Tests: 3 reactMajor < 18 skips, 3 dynamic import('react-dom/client') calls and their comments removed from the SSR tests.
• Comments: 4 React 17 comments removed.
• CI: no React 17 job exists, so there is nothing to remove.
• Bundle size (CI report, gzip): 12 of 14 bundles get smaller, by 6 B to 109 B. The largest relative gain is @mui/x-tree-view (-73 B, -0.33%). @mui/x-date-pickers grows by 3 B and @mui/x-license does not change. The gain is small because the shim stays in the bundles: @base-ui/utils/store (useStore) imports it.

What stays

• @base-ui/utils and @base-ui/react keep their React 17 fallbacks (for example useGlobalId in useId and SafeReact) and their use-sync-external-store dependency, because Base UI 1.x supports React 17. 17 MUI X packages depend on @base-ui/utils, so the shim stays in the install tree and in the bundles.
• 3 useId(idProp) calls keep the wrapper because it merges the id prop (PickersTextField, CalendarGridRoot, EventTimelinePremiumEvent).
• The React 18 fallbacks for React 19 APIs stay: isReactVersionAtLeast(19) (5 places), the SafeReact read of the React internals in useDisposable, and the reactMajor < 19 and 'Activity' in React test branches.
• The @mui/material and @mui/system peer ranges do not change in this PR.

Changelog

Breaking changes

• The minimum supported version of React is now 18. Upgrade react and react-dom to v18 or v19 before you upgrade to MUI X v10. React 17 users can stay on MUI X v9.

Generated with Claude Code

[code-infra-dashboard]

Deploy preview

• docs/data/charts/quickstart/quickstart.md

  
  
• docs/data/chat/quickstart/quickstart.md

  
  
• docs/data/data-grid/quickstart/quickstart.md

  
  
• docs/data/date-pickers/quickstart/quickstart.md

  
  
• docs/data/scheduler/quickstart/quickstart.md

  
  

Bundle size

Bundle	Parsed size	Gzip size
@mui/x-data-grid	▼-17B(0.00%)	▼-70B(-0.05%)
@mui/x-data-grid-pro	▼-17B(0.00%)	▼-109B(-0.06%)
@mui/x-data-grid-premium	🔺+118B(+0.02%)	▼-72B(-0.03%)
@mui/x-charts	▼-171B(-0.04%)	▼-63B(-0.05%)
@mui/x-charts-pro	▼-149B(-0.03%)	▼-64B(-0.04%)
@mui/x-charts-premium	▼-133B(-0.02%)	▼-91B(-0.05%)
@mui/x-date-pickers	🔺+11B(+0.01%)	🔺+3B(+0.01%)
@mui/x-date-pickers-pro	🔺+5B(0.00%)	▼-6B(-0.01%)
@mui/x-tree-view	▼-191B(-0.25%)	▼-73B(-0.33%)
@mui/x-tree-view-pro	▼-200B(-0.14%)	▼-95B(-0.22%)
@mui/x-scheduler	▼-177B(-0.04%)	▼-109B(-0.09%)
@mui/x-scheduler-premium	▼-172B(-0.03%)	▼-100B(-0.06%)
@mui/x-chat	▼-204B(-0.06%)	▼-84B(-0.09%)
@mui/x-license	0B(0.00%)	0B(0.00%)

Details of bundle changes

Performance

Total duration: 1,674.05 ms +210.82 ms^(+14.4%) | Renders: 63 ⁽⁺⁰⁾ | Paint: 2,328.73 ms +314.24 ms^(+15.6%)

Test	Duration	Renders
SparkLineChart grid of 100 instances	228.24 ms 🔺+127.37 ms(+126.3%)	1 (+0)
BarChart stacked with multiple series	82.97 ms 🔺+17.70 ms(+27.1%)	2 (+0)
BarChartPro with big data amount	42.82 ms 🔺+12.01 ms(+39.0%)	2 (+0)
RadialLineChart with big data amount	52.40 ms 🔺+9.65 ms(+22.6%)	2 (+0)
HeatmapPremium: 100x100 grid (webgl renderer)	27.27 ms 🔺+5.41 ms(+24.7%)	5 (+0)

…and 9 more (+12 within noise) — details

Metric alarms

Test	Metric	Change
SparkLineChart grid of 100 instances	bench:paint	🔺 +198.23 ms
BarChart stacked with multiple series	bench:paint	🔺 +22.32 ms
HeatmapPremium: 100x100 grid (webgl renderer)	bench:paint	🔺 +5.81 ms
PieChart with big data amount	bench:paint	🔺 +3.88 ms
ScatterChartPro with big data amount and zoomed in (batch renderer)	bench:paint	🔺 +2.93 ms

…and 3 more metric alarms — details

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