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

After migrating application from angular 5 to 6, on running ng serve the following errors pop up.

Schema validation failed with the following errors: Data path "" should NOT have additional properties(project). Error: Schema validation failed with the following errors: Data path "" should NOT have additional properties(project). at MergeMapSubscriber._registry.compile.pipe.operators_1.concatMap.validatorResult [as project] (.../TemplateApp/me-cmf-web-template-angular/node_modules/@angular-devkit/core/src/workspace/workspace.js:210:42) at MergeMapSubscriber._tryNext (/.../me-cmf-web-template-angular/node_modules/@angular-devkit/core/node_modules/rxjs/internal/operators/mergeMap.js:65:27) at MergeMapSubscriber._next (.../me-cmf-web-template-angular/node_modules/@angular-devkit/core/node_modules/rxjs/internal/operators/mergeMap.js:55:18) at MergeMapSubscriber.Subscriber.next (/home/training/Attinad_Projects/TemplateApp/me-cmf-web-template-angular/node_modules/@angular-devkit/core/node_modules/rxjs/internal/Subscriber.js:64:18) at MergeMapSubscriber.notifyNext (.../TemplateApp/me-cmf-web-template-angular/node_modules/@angular-devkit/core/node_modules/rxjs/internal/operators/mergeMap.js:84:26) at InnerSubscriber._next (.../me-cmf-web-template-angular/node_modules/@angular-devkit/core/node_modules/rxjs/internal/InnerSubscriber.js:25:21) at InnerSubscriber.Subscriber.next (/.../me-cmf-web-template-angular/node_modules/@angular-devkit/core/node_modules/rxjs/internal/Subscriber.js:64:18) at MapSubscriber._next (.../me-cmf-web-template-angular/node_modules/@angular-devkit/core/node_modules/rxjs/internal/operators/map.js:52:26) at MapSubscriber.Subscriber.next (/.../me-cmf-web-template-angular/node_modules/@angular-devkit/core/node_modules/rxjs/internal/Subscriber.js:64:18) at SwitchMapSubscriber.notifyNext (.../me-cmf-web-template-angular/node_modules/@angular-devkit/core/node_modules/rxjs/internal/operators/switchMap.js:77:26)

I assume that the error is with .angular.json file which I re-named from .angular-cli.json .

My .angular.json file is as follows :

{
    "$schema": "./node_modules/@angular/cli/lib/config/schema.json",
    "project": {
        "name": "mediaweb"
    },
    "apps": [{
            "root": "src",
            "outDir": "dist/browser",
            "assets": [
                "assets",
                "favicon.ico"
            ],
            "index": "index.html",
            "main": "main.ts",
            "polyfills": "polyfills.ts",
            "test": "test.ts",
            "tsconfig": "tsconfig.app.json",
            "testTsconfig": "tsconfig.spec.json",
            "prefix": "app",
            "styles": [
                "styles.scss",
                "../node_modules/owl.carousel/dist/assets/owl.carousel.css",
                "../node_modules/owl.carousel/dist/assets/owl.theme.default.css",
                "../node_modules/video.js/dist/video-js.css"
            ],
            "scripts": [
                "../node_modules/jquery/dist/jquery.js",
                "../node_modules/owl.carousel/dist/owl.carousel.js",
                "../node_modules/video.js/dist/ie8/videojs-ie8.js",
                "../node_modules/video.js/dist/video.js"
            ],
            "environmentSource": "environments/environment.ts",
            "environments": {
                "dev": "environments/environment.dev.ts",
                "prod": "environments/environment.prod.ts"
            }
        },
        {
            "platform": "server",
            "root": "src",
            "outDir": "dist/server",
            "assets": [
                "assets",
                "favicon.ico"
            ],
            "index": "index.html",
            "main": "main.server.ts",
            "test": "test.ts",
            "tsconfig": "tsconfig.server.json",
            "testTsconfig": "tsconfig.spec.json",
            "prefix": "app",
            "styles": [
                "styles.scss"
            ],
            "scripts": [],
            "environmentSource": "environments/environment.ts",
            "environments": {
                "dev": "environments/environment.dev.ts",
                "prod": "environments/environment.prod.ts"
            }
        }
    ],
    "e2e": {
        "protractor": {
            "config": "./protractor.conf.js"
        }
    },
    "lint": [{
            "project": "src/tsconfig.app.json",
            "exclude": ["**/node_modules/**", "**/UI/**"]
        },
        {
            "project": "src/tsconfig.spec.json",
            "exclude": "**/node_modules/**"
        },
        {
            "project": "e2e/tsconfig.e2e.json",
            "exclude": "**/node_modules/**"
        }
    ],
    "test": {
        "karma": {
            "config": "./karma.conf.js"
        }
    },
    "defaults": {
        "styleExt": "scss",
        "component": {}
    }
}

Should I re-structure the json file, if so how?.

Any help would be great.

The issue is generally because of a version mismatch in your package.json file.

In my Angular 7 app, I have changed "@angular-devkit/build-angular": "^0.800.2" to "@angular-devkit/build-angular": "~0.7.0".

Then I ran the command npm install after deleting node_modules.

Aside: Use ^ carefully. Your working code may not work in the future if there is a major change in the package used.

my app is on angular 7.2.3

remove "es5BrowserSupport": true from angular.json. and npm start now works.

When i was getting version error issues,Following command worked for me:

First run:

npm update

Second run:

ng update

Third run: (It will update all the mismatching packages)

ng update --all --force

First:

npm uninstall @angular-devkit/build-angular

Next:

npm install @angular-devkit/[email protected]

Angular Upgrade from 9 to 10 is very easy (all additional detail-information is here: https://update.angular.io/?v=9.0-10.0) :

Make sure your package file is in version control and all changes have been committed. This will overwrite your package file. Better you try it in a new experimental branch.

npm install -g npm-check-updates
ncu -u
ng update --all --force

In the new schema, it is no longer allowed to use the key es5BrowserSupport; remove the following line in your angular.json:

"es5BrowserSupport": true

then simply start your application anew:

npm start