Class 'FieldNode' incorrectly implements interface 'FieldState<unknown, string | number>' #67246
Description
Which @angular/* package(s) are the source of the bug?
forms
Is this a regression?
Yes
Description
Error compiling App while using signal forms
The following import statement triggers the error:
import {form, required, submit} from "@angular/forms/signals";
Please provide a link to a minimal reproduction of the bug
No response
Please provide the exception or error you saw
Application bundle generation failed. [1.771 seconds] - 2026-02-24T16:30:12.837Z
✘ [ERROR] TS2420: Class 'FieldNode' incorrectly implements interface 'FieldState<unknown, string | number>'.
Types of property 'max' are incompatible.
Type 'Signal<number | undefined> | undefined' is not assignable to type 'Signal<number | undefined>'.
Type 'undefined' is not assignable to type 'Signal<number | undefined>'.
Type 'undefined' is not assignable to type '() => number | undefined'. [plugin angular-compiler]
node_modules/@angular/forms/types/_structure-chunk.d.ts:1752:14:
1752 │ declare class FieldNode implements FieldState<unknown> {
╵ ~~~~~~~~~
Please provide the environment you discovered this bug in (run ng version)
┌───────────────────────────────────┬───────────────────┬───────────────────┐
│ Package │ Installed Version │ Requested Version │
├───────────────────────────────────┼───────────────────┼───────────────────┤
│ @angular/animations │ 21.1.5 │ ^21.1.2 │
│ @angular/build │ 21.1.5 │ ^21.1.2 │
│ @angular/cli │ 21.1.5 │ ^21.1.2 │
│ @angular/common │ 21.1.5 │ ^21.1.2 │
│ @angular/compiler │ 21.1.5 │ ^21.1.2 │
│ @angular/compiler-cli │ 21.1.5 │ ^21.1.2 │
│ @angular/core │ 21.1.5 │ ^21.1.2 │
│ @angular/forms │ 21.1.5 │ ^21.1.2 │
│ @angular/localize │ 21.1.5 │ ^21.1.2 │
│ @angular/platform-browser │ 21.1.5 │ ^21.1.2 │
│ @angular/platform-browser-dynamic │ 21.1.5 │ ^21.1.2 │
│ @angular/router │ 21.1.5 │ ^21.1.2 │
│ rxjs │ 7.8.2 │ ~7.8.0 │
│ typescript │ 5.9.3 │ ~5.9.3 │
│ zone.js │ 0.15.1 │ ~0.15.1 │
└───────────────────────────────────┴───────────────────┴───────────────────┘
Anything else?
No response