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Angular error NG01203 means a form directive cannot find a ControlValueAccessor for the element or component it is attached to. The accessor connects Angular Forms to the control’s view. Check the element named in the error first, then fix the cause: an invalid binding, a custom control without an accessor, or missing project or test configuration.
Angular’s NG01203 error documentation states: “For all custom form controls, you must register a value accessor.” The error identifies the missing connection, but not which configuration issue caused it.
What NG01203 means
Angular Forms uses a ControlValueAccessor to communicate between a form model and the control shown in the view. It writes model values to the view, reports user changes back to the model, and communicates touched and disabled state. Standard text inputs and textareas have built-in accessors; a custom control needs an appropriate accessor of its own or a suitable default one.
The error can arise for several different reasons. The binding may be on an element that is not a form control, a custom component may not register an accessor, or Angular may not have the module or test configuration that makes the control available.
#1 Best Overall
Find which element is missing an accessor
- Read the error output and identify the element or component associated with the form control.
- Search the template for
ngModel,formControl, orformControlNameon that element. - Determine whether it is a native form control, a custom component, or an element that should not have a form binding.
Angular documents ngModel on a div as an invalid example. Move the binding to a suitable control, or turn the custom element into a properly implemented form control if it is meant to accept and expose a value.
Choose the fix that matches the control
Native input or textarea
Standard text inputs and textareas already use Angular’s built-in value accessor. If NG01203 appears on one, verify that the form directive is actually attached to that native control and not to a surrounding element or wrapper component.
Custom element that behaves like a plain text input
For a custom element whose value behavior is effectively the same as a standard text input, Angular’s DefaultValueAccessor can be attached with ngDefaultControl:
<custom-input ngDefaultControl [(ngModel)]="value"></custom-input>This is appropriate only when the element can use ordinary input value behavior. A control with distinct value semantics, interaction behavior, or internal state needs a real custom accessor instead.
Rank #3
Custom component with its own value behavior
Implement ControlValueAccessor and register the component under NG_VALUE_ACCESSOR. Angular’s documented provider pattern uses useExisting, forwardRef, and multi: true:
providers: [
{
provide: NG_VALUE_ACCESSOR,
useExisting: forwardRef(() => MyInputField),
multi: true,
},
]Implement the accessor methods as a two-way bridge:
writeValue(value)updates the component’s view when the form model changes.registerOnChange(callback)stores the callback and invokes it when the user changes the control’s value.registerOnTouched(callback)stores the callback and invokes it when the control is touched, commonly on blur.setDisabledState(isDisabled)updates the control’s disabled state when Angular communicates one.
See Angular’s ControlValueAccessor API and NG_VALUE_ACCESSOR API for the interface and provider token.
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Check the component’s Angular integration documentation to confirm that it provides a value accessor and that you are using it as intended. If it does not provide one, use a supported form integration or build an adapter that implements and registers ControlValueAccessor.
Check module, test, and federation configuration
If the component itself is correctly implemented, investigate whether Angular can see it in the context where the error occurs:
- NgModule-based application: If the control is declared in a module, import that module where the control is used.
- Test only: Configure the test’s
TestBedwith the component and module dependencies needed by the template. - Nx with webpack Module Federation: Check the forms package sharing configuration described in Angular’s NG01203 documentation.
These are separate causes, not interchangeable fixes. The template and the context in which it runs determine which applies.
Quick Recap
Quick diagnosis by control type
| What has the form binding | Likely action |
|---|---|
| Native text input or textarea | Confirm the binding is on the native control, not a wrapper. |
Plain element such as a div |
Move the form binding to a suitable form control. |
| Input-like custom element with ordinary input behavior | Consider ngDefaultControl. |
| Custom component with distinct value or interaction behavior | Implement and register a ControlValueAccessor. |
| Third-party component | Verify its Angular accessor and integration requirements. |
| Error limited to a module, test, or federated app | Check the relevant module imports, TestBed dependencies, or forms-package sharing configuration. |
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