🐛 [4.19.0] Codegen fails with "Unknown prop type: undefined" errors on New Architecture

[dmk3141618]

Description

After upgrading to react-native-screens 4.19.0, builds fail with multiple Codegen errors when using New Architecture. The errors occur in several fabric component files.

Error Messages

node_modules/react-native-screens/src/fabric/SearchBarNativeComponent.ts:
Unknown prop type for "onSearchFocus": "undefined"

node_modules/react-native-screens/src/fabric/ScreenStackHeaderConfigNativeComponent.ts:
Unknown prop type for "onAttached": "undefined"

Steps to Reproduce

1. Create a React Native project with New Architecture enabled
2. Install react-native-screens@4.19.0
3. Run the build (yarn ios or yarn android)
4. Build fails with Codegen errors

Root Cause Analysis

Issue 1: | null union type in SearchBarNativeComponent.ts

In src/fabric/SearchBarNativeComponent.ts (lines 40-44, 63-64), event handler props use | null union type:

onSearchFocus?: CT.DirectEventHandler<SearchBarEvent> | null;
onSearchBlur?: CT.DirectEventHandler<SearchBarEvent> | null;
onSearchButtonPress?: CT.DirectEventHandler<SearchButtonPressedEvent> | null;
onCancelButtonPress?: CT.DirectEventHandler<SearchBarEvent> | null;
onChangeText?: CT.DirectEventHandler<ChangeTextEvent> | null;
// ...
onClose?: CT.DirectEventHandler<SearchBarEvent> | null;
onOpen?: CT.DirectEventHandler<SearchBarEvent> | null;

The React Native Codegen TypeScript parser doesn't recognize | null union types and interprets them as undefined.

Issue 2: Potential issues in ScreenStackHeaderConfigNativeComponent.ts

In src/fabric/ScreenStackHeaderConfigNativeComponent.ts:

• Line 50: backTitleVisible?: CT.WithDefault<boolean, 'true'> - string 'true' used as default for boolean type
• Lines 75-76: CT.UnsafeMixed[] type may cause Codegen parsing issues

backTitleVisible?: CT.WithDefault<boolean, 'true'>;  // should be `true` not `'true'`?
headerLeftBarButtonItems?: CT.UnsafeMixed[];
headerRightBarButtonItems?: CT.UnsafeMixed[];

Suggested Fix

For SearchBarNativeComponent.ts

Remove the | null union from event handler type definitions:

- onSearchFocus?: CT.DirectEventHandler<SearchBarEvent> | null;
+ onSearchFocus?: CT.DirectEventHandler<SearchBarEvent>;

The ? optional modifier already handles the case where these props might not be provided.

Workaround

Using patch-package to remove | null from SearchBarNativeComponent.ts resolves the first error, but then the ScreenStackHeaderConfigNativeComponent.ts error appears.

patches/react-native-screens+4.19.0.patch (partial fix)

diff --git a/node_modules/react-native-screens/src/fabric/SearchBarNativeComponent.ts b/node_modules/react-native-screens/src/fabric/SearchBarNativeComponent.ts
index df774b9..51864ad 100644
--- a/node_modules/react-native-screens/src/fabric/SearchBarNativeComponent.ts
+++ b/node_modules/react-native-screens/src/fabric/SearchBarNativeComponent.ts
@@ -37,11 +37,11 @@ type AutoCapitalizeType =
 type OptionalBoolean = 'undefined' | 'false' | 'true';

 export interface NativeProps extends ViewProps {
-  onSearchFocus?: CT.DirectEventHandler<SearchBarEvent> | null;
-  onSearchBlur?: CT.DirectEventHandler<SearchBarEvent> | null;
-  onSearchButtonPress?: CT.DirectEventHandler<SearchButtonPressedEvent> | null;
-  onCancelButtonPress?: CT.DirectEventHandler<SearchBarEvent> | null;
-  onChangeText?: CT.DirectEventHandler<ChangeTextEvent> | null;
+  onSearchFocus?: CT.DirectEventHandler<SearchBarEvent>;
+  onSearchBlur?: CT.DirectEventHandler<SearchBarEvent>;
+  onSearchButtonPress?: CT.DirectEventHandler<SearchButtonPressedEvent>;
+  onCancelButtonPress?: CT.DirectEventHandler<SearchBarEvent>;
+  onChangeText?: CT.DirectEventHandler<ChangeTextEvent>;
   hideWhenScrolling?: CT.WithDefault<boolean, true>;
   autoCapitalize?: CT.WithDefault<AutoCapitalizeType, 'systemDefault'>;
   placeholder?: string;
@@ -60,8 +60,8 @@ export interface NativeProps extends ViewProps {
   disableBackButtonOverride?: boolean;
   // TODO: consider creating enum here
   inputType?: string;
-  onClose?: CT.DirectEventHandler<SearchBarEvent> | null;
-  onOpen?: CT.DirectEventHandler<SearchBarEvent> | null;
+  onClose?: CT.DirectEventHandler<SearchBarEvent>;
+  onOpen?: CT.DirectEventHandler<SearchBarEvent>;
   hintTextColor?: ColorValue;
   headerIconColor?: ColorValue;
   shouldShowHintSearchIcon?: CT.WithDefault<boolean, true>;

Current workaround: Downgrade to react-native-screens@4.18.0

Environment

• react-native-screens: 4.19.0
• react-native: 0.81.0
• expo: 54.0.1
• Architecture: New Architecture enabled
• Platform: iOS / Android

Related

• Codegen Missing Features Discussion - Documents Codegen's limited TypeScript type support
• Version 4.18.0 works correctly with the same setup

[github-actions]

Hey! 👋

It looks like you've omitted a few important sections from the issue template.

Please complete Steps to reproduce, Snack or a link to a repository, Screens version, React Native version and Platforms sections.

[github-actions]

Hey! 👋

The issue doesn't seem to contain a minimal reproduction.

Could you provide a snack or a link to a GitHub repository under your username that reproduces the problem?

[kkafar]

Hey! Thanks for the report here. I don't experience such problems on my end, but we'll try to reproduce this on setup you described.

[naheedsa]

I guess i am facing similiar issue:

node_modules/@react-native/codegen/lib/parsers/typescript/components/componentsUtils.js:410
throw new Error(Unknown prop type for "${name}": "${type}");
^

Error: Unknown prop type for "environment": "undefined"

[nitin251199]

+1 @naheedsa

[dhanasekarancm]

Facing the same problem

Task :react-native-screens:generateCodegenSchemaFromJavaScript FAILED Error: Unknown prop type for "environment": "undefined" at getTypeAnnotation ... at buildPropSchema ...

It seems related to Codegen not recognizing the environment prop type. I’m using Node.js 24 and React Native with the ^4.10.0 react-native-screens release. The error occurs even after upgrading react-native-screens and cleaning caches.

[kkafar]

If anybody is able to provide an issue reproducer, that would simplify the fix process

[t0maboro]

TL;DR
For all codegen-related issues, as the first step, please ensure that the react-native version and react-native-screens version are compatible. ref. https://github.com/software-mansion/react-native-screens/blob/main/README.md#support-for-fabric

---

Hi,
In version 4.19.0, we started a migration process to stable JS APIs for react-native-screens. Please note that the minimal compatible React Native version with react-native-screens on Fabric is now 0.81.

react-native: 0.79.0
react-native-screens: 4.19.0

I'm able to reproduce both:

[Codegen] Error: Unknown prop type for "environment": "undefined"
[Codegen] Done.

and

/Users/tomaszboron/AwesomeProject79/node_modules/@react-native/codegen/lib/parsers/typescript/components/componentsUtils.js:410
  throw new Error(Unknown prop type for "${name}": "${type}");
                              ^

On the other hand, using RN 0.81 I was unable to reproduce this issue.

This issue should never happen with RN 0.81. It'd be great if someone is able to share a repro if it happened. That would help us investigate further. Thank you!

[bilalali-eng]

Facing similar issue all of a sudden pod install starts failing:

[Codegen] Searching for podspec in the project dependencies.
[Codegen] Supported Apple platforms: ios, tvos, visionos for rnscreens

[Codegen] Error: Unknown prop type for "environment": "undefined"

Any Solution?

[irinagastmaier]

Hi, I am also able to reproduce it:

"react-native": "0.81.5",
"expo": "~54.0.30",
"react": "19.1.0",
"react-native-screens": "~4.19.0",

node_modules/react-native-screens/src/fabric/SearchBarNativeComponent.ts: Unknown prop type for "onSearchFocus": "undefined"

node_modules/react-native-screens/src/fabric/ScreenStackNativeComponent.ts: Unknown prop type for "onFinishTransitioning": "undefined"