Incompatible peer dependencies found - upgrading Angular from 8 to 9

Question

I am following the official document to upgrade.

This step completed without any errors.

ng update @angular/core@8 @angular/cli@8 

Next step failed.

ng update @angular/core @angular/cli The installed Angular CLI version is older than the latest stable version. Installing a temporary version to perform the update. Installing packages for tooling via npm. Installed packages for tooling via npm. Using package manager: 'npm' Collecting installed dependencies... Found 45 dependencies. Fetching dependency metadata from registry...                   Package "@angular/core" has a missing peer dependency of "tslib" @ "^1.10.0".                   Package "@angular/animations" has a missing peer dependency of "tslib" @ "^1.10.0".                   Package "@angular/compiler" has a missing peer dependency of "tslib" @ "^1.10.0".                   Package "@angular/forms" has a missing peer dependency of "tslib" @ "^1.10.0".                   Package "@angular/common" has a missing peer dependency of "tslib" @ "^1.10.0".                   Package "@angular/platform-browser" has a missing peer dependency of "tslib" @ "^1.10.0".                   Package "@angular/compiler-cli" has a missing peer dependency of "tslib" @ "^1.10.0".                   Package "@angular/router" has a missing peer dependency of "tslib" @ "^1.10.0".                   Package "@angular/platform-browser-dynamic" has a missing peer dependency of "tslib" @ "^1.10.0".                   Package "@ngtools/webpack" has an incompatible peer dependency to "typescript" (requires ">=3.4 < 3.6", would install "3.7.5"). Incompatible peer dependencies found. Peer dependency warnings when installing dependencies means that those dependencies might not work correctly together. You can use the '--force' option to ignore incompatible peer dependencies and instead address these warnings later.  

I checked the node_modules and the correct version of tslib is installed. I manually added the tslib entry and ran npm install to see if the error goes away.

  "dependencies": {     "@angular/animations": "^8.2.14",     "@angular/common": "^8.2.14",     "@angular/compiler": "^8.2.14",     "@angular/core": "^8.2.14",     "@angular/forms": "^8.2.14",     "@angular/language-service": "^8.2.14",     "@angular/platform-browser": "^8.2.14",     "@angular/platform-browser-dynamic": "^8.2.14",     "@angular/router": "^8.2.14",     "@ng-bootstrap/ng-bootstrap": "^5.3.0",     "classlist.js": "^1.1.20150312",     "core-js": "^3.6.4",     "npm": "^6.13.7",     "rxjs": "^6.5.4",     "web-animations-js": "^2.3.2",     "zone.js": "~0.9.1"   },   "devDependencies": {     "@angular-devkit/architect": "^0.803.25",     "@angular-devkit/build-angular": "^0.803.25",     "@angular-devkit/build-optimizer": "^0.803.25",     "@angular-devkit/build-webpack": "^0.803.25",     "@angular-devkit/core": "^8.3.25",     "@angular-devkit/schematics": "^8.3.25",     "@angular/cli": "^8.3.25",     "@angular/compiler-cli": "^8.2.14",     "@ngtools/webpack": "^8.3.25",     "@schematics/angular": "^8.3.25",     "@schematics/update": "^0.803.25",     "@types/jasmine": "^3.5.4",     "@types/jasminewd2": "^2.0.8",     "@types/node": "^12.12.27",     "tslib": "^1.10.0",     "codelyzer": "^5.2.1",     "jasmine-core": "^3.5.0",     "jasmine-spec-reporter": "~4.2.1",     "karma": "^4.4.1",     "karma-chrome-launcher": "~3.1.0",     "karma-coverage-istanbul-reporter": "^2.1.1",     "karma-jasmine": "~2.0.1",     "karma-jasmine-html-reporter": "^1.5.2",     "protractor": "^5.4.3",     "rxjs-tslint": "^0.1.7",     "ts-node": "^8.6.2",     "tslint": "^5.20.1",     "typescript": "~3.4",     "webpack": "^4.41.6",     "webpack-dev-server": "^3.10.3"   } 

ng v output

Angular CLI: 8.3.25 Node: 12.13.0 OS: win32 x64 Angular: 8.2.14 ... animations, common, compiler, compiler-cli, core, forms ... language-service, platform-browser, platform-browser-dynamic ... router  Package                           Version ----------------------------------------------------------- @angular-devkit/architect         0.803.24 @angular-devkit/build-angular     0.803.25 @angular-devkit/build-optimizer   0.803.24 @angular-devkit/build-webpack     0.803.25 @angular-devkit/core              8.3.24 @angular-devkit/schematics        8.3.24 @angular/cli                      8.3.25 @ngtools/webpack                  8.3.24 @schematics/angular               8.3.24 @schematics/update                0.803.24 rxjs                              6.5.4 typescript                        3.4.5 webpack                           4.41.5 

I haven't tried to use --force option. Is there another way?

Answer 1

Looks like you glanced over one of the errors:

Package "@ngtools/webpack" has an incompatible peer dependency to "typescript" (requires ">=3.4 < 3.6", would install "3.7.5").

Try a lower version of @ngtools/webpack that works with TypeScript 3.4 to 3.5.

Alternatively, update your TypeScript version in the package.json to 3.7.5 and run npm update, then you should be able to update @angular/core & @angular/cli.