reflex-dev/reflex v0.9.9

on GitHub

Breaking Changes

• pip install reflex no longer installs pydantic; pydantic model support activates when it is installed. Use the new reflex[pydantic] extra (or reflex[db]) to keep it. (#6786)
• The compiled frontend now targets React Router 8.3.0 (from 7.18.2), and Reflex requires Node 22.22.0 or newer as a result. Apps on the default generated setup need no rxconfig.py or app code changes. One change is required if you wrote a custom component against react-router-dom: that package no longer exists upstream and is no longer installed, so library = "react-router-dom" must become react-router (or react-router/dom for RouterProvider/HydratedRouter). (#6854)
• A RegistrationContext can only be associated with a single App instance, so creating a second bare rx.App() in one process now raises ReflexRuntimeError (0.9.8 allowed it); use a fresh RegistrationContext (e.g. RegistrationContext.fork()) to create multiple apps. (#6382)

Deprecations

• reflex.components.dynamic.bundled_libraries and DEFAULT_BUNDLED_LIBRARIES are deprecated (removal in 1.0) but keep working, resolving against the active RegistrationContext. Use RegistrationContext.ensure_context().bundled_libraries to read the list, or bundle_library() / reset_bundled_libraries() to modify it. (#6967)
• reflex.page.DECORATED_PAGES is deprecated (removal in 1.0) but keeps working, resolving to a mapping of the app name to the active RegistrationContext's page registrations. Use RegistrationContext.ensure_context().decorated_pages instead. (#6985)

Features

• The current App, the loaded Config, @rx.page registrations, and the bundled-library registry are now scoped to the active RegistrationContext instead of module-level globals, so multiple apps (and test harnesses) can coexist in one process without leaking registrations into each other. (#6382)
• Report state deltas the frontend cannot process back to the backend via a new client_error socket event, logging an actionable error in the terminal instead of failing silently. A frontend/backend state mismatch is fatal for the session: further events stop until the page is reloaded after the frontend is rebuilt or api_url is corrected. (#6827)
• Framework logging now flows through standard python logging with per-module loggers (reflex_base.utils.log, re-exported as reflex.utils.log), bootstrapped on import reflex. Rich colored output is preserved, and REFLEX_LOG_JSON emits machine-readable JSON-lines records. --loglevel critical no longer prints the system-info banner. (#6863)
• The reflex CLI accepts --json (equivalent to REFLEX_LOG_JSON) to emit machine-readable JSON-lines logs. (#6865)
• reflex deploy accepts --min-instances and --max-instances to set the autoscaling bounds of an app deployed to Google Cloud. Omitted bounds are left unchanged. (#6884)
• reflex deploy gains --gcp-connection, to pick which of your organization's connected GCP accounts an app deploys through; --full-deploy, to serve the frontend from the provider's own container instead of Reflex's CDN; and --strategy, which was previously only settable in the config file. (#6908)
• Compiled components are now named for React DevTools: memoized components take a displayName from the Python class or @rx.memo function they came from instead of showing as Anonymous, generated contexts are named (StateContext(reflex___state____state.my_state).Provider rather than an unlabelled Context.Provider), pages are labelled with their route (Component(blog/[slug])), and client-only (NoSSRComponent) wrappers render as ClientSide(<Tag>). (#6945)

Bug Fixes

• Stale on_load work no longer blocks or outlives a page navigation: a newer navigation for the same client now cancels the previous page's unfinished on_load event chain, including on_load handlers that are background tasks (@rx.event(background=True)), which 0.9.8 let run to completion. Background tasks started from other events are unaffected. (#6593)
• A [[...splat]] catchall route no longer matches paths that merely share its prefix — posts/[[...splat]] matched /postsomething as well as /posts and its descendants, so the wrong page's on_load events could fire. (#6790)
• Ensure state manager instances use isolated internal locks instead of sharing one lock across instances. (#6830)
• Qualify dict annotations on BaseState that were shadowed by BaseState.dict, so type checkers resolve them to the builtin. (#6846)
• reflex run now pre-enables the development export condition for the dev server via NODE_OPTIONS/BUN_OPTIONS, fixing the dev server exiting with restartWithMergedOptions() was called, but the process has already been restarted on installs without node, where react-router 8's CLI re-executes itself to set the condition. (#6857)
• An AppHarnessProd no longer leaks REFLEX_ENV_MODE=prod to dev AppHarness instances created later in the same process, which made them compile with route prerendering enabled and drop events dispatched during hydration recovery. (#6857)
• Cache event handler annotations before runtime state-class patches can shadow builtin names on Python 3.14. (#6890)
• rx.script head updates now flush synchronously instead of via react-helmet's requestAnimationFrame batching, fixing intermittently missing script tags after hydration (flaky "scripts not loaded" failures). (#6905)
• Fixed a race where a finishing background task could silently discard state updates made by a concurrently running event handler before they reached the frontend, leaving the UI stale until the next write. Background handlers that never enter async with self still emit their delta, now computed under the state lock. (#6920)
• AppHarness starts the frontend dev server with the development export condition enabled, fixing "Frontend did not start" on node-less (bun-only) installs where react-router's dev CLI restart guard trips. (#6931)
• Adding a page no longer raises a spurious RouteValueError when a static segment lines up with another route's dynamic segment (e.g. /posts/all/[x] alongside /posts/[id]). React Router resolves such siblings in favor of the static one, so only two differently named dynamic segments at the same position conflict. The check was also order-dependent: it only tripped when the bracket-carrying route was added second. (#6953)
• Reduce published wheel and sdist size by removing misplaced generated artifacts. (#6966)
• A client_error socket emit with no payload no longer raises an unhandled TypeError inside python-socketio's dispatch, which let any connected socket — even one without a valid token — spam asyncio tracebacks into the backend logs past the handler's rate limits. (#6984)
• Console warnings and errors no longer print literal backslash-escaped brackets (e.g. dict\[str, str]). The rich-markup escapes were left over from the legacy console helpers, but the logging pipeline renders messages with markup disabled, so bracketed type names now print verbatim. VarAttributeError messages drop the same escapes. (#6989)
• reflex run no longer hangs forever when a fatal error (e.g. the node minimum-version check on the npm path) exits the frontend worker thread while the backend blocks the main thread; the failure now interrupts the main thread and the CLI exits promptly with the original error. (#6990, #6994)

Performance

• Remove the per-update asyncio.create_task wrapper in EventNamespace.emit_update, cutting scheduling overhead roughly in half for every outgoing state update. (#6734)
• Dev mode no longer pays for React's per-element owner-stack capture: navigation clicks in a large app dropped from ~350ms to ~83ms of main-thread CPU (5.6x prod down to ~1.3x). In exchange React.captureOwnerStack() returns no owner frames in dev, which affects React DevTools' owner-stack view and custom error overlays built on that API; set REFLEX_REACT_OWNER_STACKS=1 to restore them. (#6905)
• @rx.memo components with props bound to state are now auto-memoized at the call site: the state hooks those props need compile into a generated wrapper component instead of the page module. A state change re-renders that wrapper rather than the whole page, and React's memo stops there unless one of the prop values actually changed. (#6949)
• The generated vite.config.js now declares a hook filter on the plugin that redirects react-dom/server to react-dom/server.node, so the bundler no longer calls into it for every import in the module graph — on the Reflex docs site that was ~15,800 calls per build to rewrite a single specifier. (#6959)

Documentation

• Documented the provider, gcp_connection and full_deploy cloud config settings, including which settings a Google Cloud target ignores and why full_deploy is left unset rather than false by default. (#6908)

Miscellaneous

• The generated package.json no longer carries a framework-owned postcss override; the pinned postcss dev dependency already forces a single resolved copy for every transitive requirer. Projects that already installed 0.9.8 keep an inert "postcss": "8.5.23" override in reflex.lock/package.json; it matches the dev-dependency pin, so it changes nothing today and can be deleted by hand. (#6854)
• Upgrade the locked dev tooling: ruff 0.15.12 -> 0.16.2, pyright 1.1.408 -> 1.1.411, typer 0.25.1 -> 0.27.1. (#6893)
• The reflex deploy command implementation moved out of the reflex package into reflex-hosting-cli, so cloud code is no longer shipped inside the framework. Flags and behavior are unchanged, and reflex-hosting-cli remains a dependency of reflex, so reflex deploy and reflex cloud stay available out of the box. If the package is not installed, these commands now report which package to install instead of failing with a missing-command error. (#6924)