The primary reason for this error is that Angular 6 has changed its schema validation rules. Specifically, the "project" property should not have additional properties.Another possible cause is that there may be a mismatch between the old and new schema definitions in your application.

How do I fix: Check for schema migration issues using the CLI?

Step 1: Run the "ng migrate:apply" command to check for any schema migration issues in your application.Step 2: Address any errors or warnings reported by the command, following the recommended fixes and updates.

Coding⏱️ 3 min read📅 2026-06-04

How to Fix: Error: Schema validation failed with the following errors: Data path "" should NOT have additional properties(project)

Q: Best Solutions to Fix It Update the project structure to conform to the new Angular 6 schema?

Step 1: Open the project's "angular.json" file and update the "projects" section to use the new "project" property format.Step 2: Remove any additional properties from the "project" object, as they are no longer supported in Angular 6.Step 3: Restart the ng serve command to apply the changes.

Angular schema validation error due to additional properties in JSON data.

Quick Answer: Remove any unnecessary properties from your JSON data to resolve the issue.

📋 Table of Contents

⚠️ Common Causes
✅ Best Solutions to Fix It
💡 Conclusion

Error: Schema validation failed with the following errors: Data path "" should NOT have additional properties(project). This error occurs when migrating an Angular application from version 5 to 6, and it affects developers who are running ng serve.

This error can be frustrating as it prevents the application from serving properly. However, by following the steps outlined in this guide, you will be able to resolve the issue and get your application up and running again.

⚠️ Common Causes

The primary reason for this error is that Angular 6 has changed its schema validation rules. Specifically, the "project" property should not have additional properties.
Another possible cause is that there may be a mismatch between the old and new schema definitions in your application.

✅ Best Solutions to Fix It

Update the project structure to conform to the new Angular 6 schema

Step 1: Open the project's "angular.json" file and update the "projects" section to use the new "project" property format.
Step 2: Remove any additional properties from the "project" object, as they are no longer supported in Angular 6.
Step 3: Restart the ng serve command to apply the changes.

Check for schema migration issues using the CLI

Step 1: Run the "ng migrate:apply" command to check for any schema migration issues in your application.
Step 2: Address any errors or warnings reported by the command, following the recommended fixes and updates.

💡 Conclusion

By following these steps, you should be able to resolve the Schema validation failed error and get your Angular 6 application up and running again. Remember to regularly update your schema definitions to ensure compatibility with future versions of Angular.

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