[SOLVED] Could not resolve dependency: npm ERR! peer @angular/compiler@"11.2.8"

Could not resolve dependency: npm ERR! peer @angular/compiler@"11.2.8"

I am trying to get my app to deploy on Heroku. I was getting the "sh: 1: ng: not found" error but based on responses on here, I moved my @angular/cli, @angular-devkit/build-angular, @angular/compiler-cli, and typescript. Now I am getting a "Could not resolve dependency: npm ERR! peer @angular/compiler@"11.2.8"" error. I think it is having a versioning issue? I'm not sure what is going on.

I've tried running 'npm update' and tried manually inserting the '@angular/compiler@"11.2.8"' to dependencies and then running 'npm i' but both give me this same error.

Here is my error:

npm ERR! Found: @angular/compiler@11.0.9
npm ERR! node_modules/@angular/compiler
npm ERR!   @angular/compiler@"~11.0.1" from the root project
npm ERR!
npm ERR! Could not resolve dependency:
npm ERR! peer @angular/compiler@"11.2.8" from @angular/compiler-cli@11.2.8
npm ERR! node_modules/@angular/compiler-cli
npm ERR!   dev @angular/compiler-cli@"^11.0.9" from the root project
npm ERR!   peer @angular/compiler-cli@"^11.0.0" from @angular-devkit/build-angular@0.1100.7
npm ERR!   node_modules/@angular-devkit/build-angular
npm ERR!     @angular-devkit/build-angular@"~0.1100.2" from the root project

Package.json:

"scripts": {
    "ng": "ng",
    "start": "ng serve",
    "build": "ng build",
    "test": "ng test",
    "lint": "ng lint",
    "e2e": "ng e2e",
    "postinstall": "ngcc"
  },
  "private": true,
  "dependencies": {
    "@angular-devkit/build-angular": "~0.1100.2",
    "@angular/animations": "~11.0.1",
    "@angular/cdk": "^11.2.6",
    "@angular/cli": "~11.0.2",
    "@angular/common": "~11.0.1",
    "@angular/compiler": "~11.0.1",
    "@angular/core": "~11.0.1",
    "@angular/flex-layout": "^11.0.0-beta.33",
    "@angular/forms": "~11.0.1",
    "@angular/material": "^11.2.6",
    "@angular/platform-browser": "~11.0.1",
    "@angular/platform-browser-dynamic": "~11.0.1",
    "@angular/router": "~11.0.1",
    "angular-in-memory-web-api": "^0.11.0",
    "rxjs": "~6.6.0",
    "tslib": "^2.0.0",
    "typescript": "~4.0.2",
    "uuid": "^3.4.0",
    "zone.js": "~0.10.2"
  },
  "devDependencies": {
    "@angular-devkit/build-angular": "~0.1100.2",
    "@angular/cli": "~11.0.2",
    "@angular/compiler-cli": "^11.0.9",
    "@types/jasmine": "~3.6.0",
    "@types/node": "^12.11.1",
    "codelyzer": "^6.0.0",
    "jasmine-core": "~3.6.0",
    "jasmine-spec-reporter": "~5.0.0",
    "karma": "~5.1.0",
    "karma-chrome-launcher": "~3.1.0",
    "karma-coverage": "~2.0.3",
    "karma-jasmine": "~4.0.0",
    "karma-jasmine-html-reporter": "^1.5.0",
    "protractor": "~7.0.0",
    "ts-node": "~8.3.0",
    "tslint": "~6.1.0",
    "typescript": "~4.0.2"
  }

How does one resolve this error?

Solution

In addition to using the npm install --save --legacy-peer-deps command line option, this can also be set more permanently as a config option: npm config set legacy-peer-deps true.

If above approach does not work try removing the node_modules folder and package-lock.json file and run command npm install.