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Jan 06, 2021 2 mins

Resolving Angular Error NG0300 Multiple Components Match Node with Tagname

Learn Angular Learn Angular

Angular applications provide a robust framework for building dynamic and interactive web applications. However, like any technology, challenges can arise, and error messages such as `ERROR Error: Uncaught (in promise): Error: NG0300: Multiple components match node with tagname button: MatButton and MatIconButton`` can be encountered. This error typically occurs when multiple Angular components are competing for the same DOM element, leading to conflicts and runtime issues. In this guide, we will explore the potential causes of this error and provide a step-by-step solution to resolve it.

Understanding the Error

The NG0300 error is a runtime error that indicates a conflict in the Angular application’s component structure. In this specific case, the error is related to a button element with multiple Angular Material components applied to it, specifically MatButton and MatIconButton. Angular is unable to determine which component should handle the button, leading to the error.

Identifying the Culprit Code

To begin resolving the error, let’s examine the code snippet.

<button mat-button matSuffix mat-icon-button color="primary">
  <mat-icon class="search-icon" *ngIf="value != ''; else elseBlock" (click)="value=''">close</mat-icon>
  <ng-template #elseBlock>
    <mat-icon class="search-icon">search</mat-icon>
  </ng-template>
</button>

In this snippet, both mat-button and mat-icon-button directives are used on the same button element. This combination can lead to conflicts and trigger the NG0300 error.

Resolving the NG0300 Error

To resolve the NG0300 error, follow these steps

Choose One Button Directive
Decide whether you want a regular Material Design button (mat-button) or an icon button (mat-icon-button). Using both simultaneously on the same button can cause conflicts. Choose the directive that aligns with your design preferences and application requirements.

Example using mat-button:

<button mat-button color="primary">
  <mat-icon class="search-icon" *ngIf="value != ''; else elseBlock" (click)="value=''">close</mat-icon>
  <ng-template #elseBlock>
    <mat-icon class="search-icon">search</mat-icon>
  </ng-template>
</button>

Example using mat-icon-button

<button mat-icon-button color="primary">
  <mat-icon class="search-icon" *ngIf="value != ''; else elseBlock" (click)="value=''">close</mat-icon>
  <ng-template #elseBlock>
    <mat-icon class="search-icon">search</mat-icon>
  </ng-template>
</button>

Remove Redundant Directives
Once you have chosen a button directive, remove any redundant directives. In this case, you can remove either mat-button or mat-icon-button based on your decision in step 1.

Ensure Consistent Angular Material Versions
Verify that all your Angular Material packages (@angular/material, @angular/cdk, and @angular/flex-layout) are using compatible versions. Mismatched versions can lead to unexpected behavior. Update all Angular Material packages to a consistent version if necessary.

Update Angular CLI and Dependencies
Keeping your Angular CLI and other dependencies up to date is crucial for stability and compatibility. Update your Angular CLI to the latest version using the following command:

ng update @angular/cli@latest

Additionally, update other dependencies, including TypeScript, using:

ng update

Follow the prompts to apply the updates.

Review Angular Material Documentation
Consult the official Angular Material documentation for any breaking changes or updates related to the components you are using. The documentation often provides insights into common issues and their solutions.

Conclusion

By following these steps, you should be able to resolve the NG0300 error in your Angular project. Choosing a single button directive, removing redundancies, ensuring consistent Angular Material versions, and keeping your dependencies up to date are key practices for maintaining a stable and error-free Angular application. This guide aims to assist developers in identifying and resolving the NG0300 error, providing a smoother development experience.


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  • Avatar

    Danielle Carline

    Posted on

    Use one directive in the element, mat-button or mat-icon-button

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  • error ng0300
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