An Owner Stack is a string representing the components that are directly responsible for rendering a particular component. You can log Owner Stacks when debugging or use Owner Stacks to enhance error overlays or other development tools. Owner Stacks are only available in development builds. Component Stacks in production are unchanged.

An Owner Stack is a development-only stack trace that helps identify which components are responsible for rendering a particular component. An Owner Stack is distinct from a Component Stacks, which shows the hierarchy of components leading to an error.
The captureOwnerStack API is only available in development mode and returns a Owner Stack, if available. The API can be used to enhance error overlays or log component relationships when debugging. #29923, #32353, #30306, #32538, #32529, #32538

React

Enhanced support for Suspense boundaries to be used anywhere, including the client, server, and during hydration. #32069, #32163, #32224, #32252
Reduced unnecessary client rendering through improved hydration scheduling #31751
Increased priority of client rendered Suspense boundaries #31776
Fixed frozen fallback states by rendering unfinished Suspense boundaries on the client. #31620
Reduced garbage collection pressure by improving Suspense boundary retries. #31667
Fixed erroneous “Waiting for Paint” log when the passive effect phase was not delayed #31526
Fixed a regression causing key warnings for flattened positional children in development mode. #32117
Updated useId to use valid CSS selectors, changing format from :r123: to «r123». #32001
Added a dev-only warning for null/undefined created in useEffect, useInsertionEffect, and useLayoutEffect. #32355
Fixed a bug where dev-only methods were exported in production builds. React.act is no longer available in production builds. #32200
Improved consistency across prod and dev to improve compatibility with Google Closure Complier and bindings #31808
Improve passive effect scheduling for consistent task yielding. #31785
Fixed asserts in React Native when passChildrenWhenCloningPersistedNodes is enabled for OffscreenComponent rendering. #32528
Fixed component name resolution for Portal #32640
Added support for beforetoggle and toggle events on the dialog element. #32479 #32479

React DOM

Fixed double warning when the href attribute is an empty string #31783
Fixed an edge case where getHoistableRoot() didn’t work properly when the container was a Document #32321
Removed support for using HTML comments (e.g. ) as a DOM container. #32250
Added support for <script> and <template> tags to be nested within <select> tags. #31837
Fixed responsive images to be preloaded as HTML instead of headers #32445

use-sync-external-store

Added exports field to package.json for use-sync-external-store to support various entrypoints. #25231

React Server Components

Added unstable_prerender, a new experimental API for prerendering React Server Components on the server #31724
Fixed an issue where streams would hang when receiving new chunks after a global error #31840, #31851
Fixed an issue where pending chunks were counted twice. #31833
Added support for streaming in edge environments #31852
Added support for sending custom error names from a server so that they are available in the client for console replaying. #32116
Updated the server component wire format to remove IDs for hints and console.log because they have no return value #31671
Exposed registerServerReference in client builds to handle server references in different environments. #32534
Added react-server-dom-parcel package which integrates Server Components with the Parcel bundler #31725, #32132, #31799, #32294, #31741