Hey, let's work through why that error is still showing up on line 3 of your app.component.html—I've hit this exact snag before, so here are the key things to check beyond just adding a name attribute:

1. Did you forget to import FormsModule? #

This is the #1 mistake people make when using ngModel. Angular won't recognize [(ngModel)] at all unless you've imported FormsModule into your module. Double-check your AppModule (or the module where your component lives):

import { FormsModule } from '@angular/forms';

@NgModule({
  imports: [
    BrowserModule,
    FormsModule // This line is critical—don't skip it!
  ],
  declarations: [AppComponent],
  bootstrap: [AppComponent]
})
export class AppModule { }

2. Is the name attribute on the right element? #

Make sure you added name directly to the element with [(ngModel)], not a parent container. For example:

❌ Wrong:

<form>
  <div name="username"> <!-- Name is on the div, not the input -->
    <input type="text" [(ngModel)]="username"> <!-- Line 3 error here -->
  </div>
</form>

✅ Correct:

<form>
  <input type="text" name="username" [(ngModel)]="username"> <!-- Name is on the input -->
</form>

3. Are there duplicate name values in the form? #

Angular requires unique name attributes for every control inside a single <form>. If you have two inputs with the same name, it'll throw this error even if you added the attribute:

❌ Wrong:

<form>
  <input type="text" name="email" [(ngModel)]="workEmail">
  <input type="text" name="email" [(ngModel)]="personalEmail"> <!-- Duplicate name -->
</form>

✅ Correct:

<form>
  <input type="text" name="workEmail" [(ngModel)]="workEmail">
  <input type="text" name="personalEmail" [(ngModel)]="personalEmail">
</form>

4. Try the standalone option as a fallback #

If none of the above work, you can force the control to ignore the parent form by setting ngModelOptions:

<form>
  <input type="text" [(ngModel)]="username" [ngModelOptions]="{standalone: true}">
</form>

This tells Angular the control doesn't belong to the form, so it won't require a name attribute. Use this if you don't need the input to be part of the form's validation or value collection.

5. Check for nested <form> tags #

Angular doesn't support nested form elements. If you have a <form> inside another <form>, the inner controls won't be recognized properly, leading to this error:

❌ Wrong:

<form>
  <form> <!-- Nested form is invalid -->
    <input type="text" name="username" [(ngModel)]="username">
  </form>
</form>

✅ Correct:

<form>
  <div> <!-- Use a div instead of nested form -->
    <input type="text" name="username" [(ngModel)]="username">
  </div>
</form>

If you still can't fix it, feel free to share the exact code from line 3 of your app.component.html—that'll help narrow it down further!

内容的提问来源于stack exchange，提问作者elshev