ng build --prod fails with "ERROR in xx.js from Terser undefined" after upgrade to Angular 7

I am upgrading Angular 5 to Angular 7. ng build looks good but ng build with --prod flag fails with ERROR in xx.js from Terser undefined. I checked the issue 12662 but didn’t find tether npm package in my project. Now I am adding terser latest version 3.10.12 but still getting the same error.

Versions

I am using node version v11.3.0 on Ubuntu 16 Those are the dependencies in package.json

 "dependencies": {
    "@angular/animations": "7.1.1",
    "@angular/cdk": "^7.1.0",
    "@angular/common": "7.1.1",
    "@angular/compiler": "7.1.1",
    "@angular/core": "7.1.1",
    "@angular/forms": "7.1.1",
    "@angular/http": "7.1.1",
    "@angular/material": "^7.1.0",
    "@angular/platform-browser": "7.1.1",
    "@angular/platform-browser-dynamic": "7.1.1",
    "@angular/router": "7.1.1",
    "@ngx-translate/core": "^11.0.1",
    "@ngx-translate/http-loader": "^4.0.0",
    "@types/underscore": "^1.8.7",
    "angulartics2": "^7.2.0",
    "core-js": "^2.4.1",
    "hammerjs": "^2.0.8",
    "npm": "^6.4.1",
    "rxjs": "^6.3.3",
    "rxjs-compat": "^6.3.3",
    "terser": "^3.10.12",
    "tslib": "^1.9.0",
    "underscore": "^1.8.3",
    "uninstall": "0.0.0",
    "yaml-js": "^0.2.3",
    "zone.js": "^0.8.26"
  },
  "devDependencies": {
    "@angular-devkit/build-angular": "~0.11.0",
    "@angular/cli": "7.1.0",
    "@angular/compiler-cli": "7.1.1",
    "@angular/language-service": "7.1.1",
    "@types/jasmine": "~2.8.6",
    "@types/jasminewd2": "~2.0.2",
    "@types/node": "~9.6.5",
    "codelyzer": "^4.0.1",
    "jasmine-core": "^3.2.1",
    "jasmine-spec-reporter": "^4.2.1",
    "karma": "^3.0.0",
    "karma-cli": "^1.0.1",
    "karma-coverage-istanbul-reporter": "^2.0.3",
    "karma-jasmine": "^1.1.2",
    "karma-jasmine-html-reporter": "^1.3.1",
    "protractor": "^5.4.1",
    "ts-node": "~6.0.0",
    "tslint": "^5.11.0",
    "typescript": "3.1.6"
  }

Those are terser related packages in package-lock.json

 "terser": {
      "version": "3.10.12",
      "resolved": "https://registry.npmjs.org/terser/-/terser-3.10.12.tgz",
      "integrity": "sha512-3ODPC1eVt25EVNb04s/PkHxOmzKBQUF6bwwuR6h2DbEF8/j265Y1UkwNtOk9am/pRxfJ5HPapOlUlO6c16mKQQ==",
      "requires": {
        "commander": "~2.17.1",
        "source-map": "~0.6.1",
        "source-map-support": "~0.5.6"
      },
      "dependencies": {
        "commander": {
          "version": "2.17.1",
          "resolved": "https://registry.npmjs.org/commander/-/commander-2.17.1.tgz",
          "integrity": "sha512-wPMUt6FnH2yzG95SA6mzjQOEKUU3aLaDEmzs1ti+1E9h+CsrZghRlqEM/EJ4KscsQVG8uNN4uVreUeT8+drlgg=="
        },
        "source-map": {
          "version": "0.6.1",
          "resolved": "https://registry.npmjs.org/source-map/-/source-map-0.6.1.tgz",
          "integrity": "sha512-UjgapumWlbMhkBgzT7Ykc5YXUT46F0iKu8SGXq0bcwP5dz/h0Plj6enJqjz1Zbq2l5WaqYnrVbwWOWMyF3F47g=="
        },
        "source-map-support": {
          "version": "0.5.9",
          "resolved": "https://registry.npmjs.org/source-map-support/-/source-map-support-0.5.9.tgz",
          "integrity": "sha512-gR6Rw4MvUlYy83vP0vxoVNzM6t8MUXqNuRsuBmBHQDu1Fh6X015FrLdgoDKcNdkwGubozq0P4N0Q37UyFVr1EA==",
          "requires": {
            "buffer-from": "^1.0.0",
            "source-map": "^0.6.0"
          }
        }
      }
    },
    "terser-webpack-plugin": {
      "version": "1.1.0",
      "resolved": "https://registry.npmjs.org/terser-webpack-plugin/-/terser-webpack-plugin-1.1.0.tgz",
      "integrity": "sha512-61lV0DSxMAZ8AyZG7/A4a3UPlrbOBo8NIQ4tJzLPAdGOQ+yoNC7l5ijEow27lBAL2humer01KLS6bGIMYQxKoA==",
      "dev": true,
      "requires": {
        "cacache": "^11.0.2",
        "find-cache-dir": "^2.0.0",
        "schema-utils": "^1.0.0",
        "serialize-javascript": "^1.4.0",
        "source-map": "^0.6.1",
        "terser": "^3.8.1",
        "webpack-sources": "^1.1.0",
        "worker-farm": "^1.5.2"
      },
      "dependencies": {
        "find-cache-dir": {
          "version": "2.0.0",
          "resolved": "https://registry.npmjs.org/find-cache-dir/-/find-cache-dir-2.0.0.tgz",
          "integrity": "sha512-LDUY6V1Xs5eFskUVYtIwatojt6+9xC9Chnlk/jYOOvn3FAFfSaWddxahDGyNHh0b2dMXa6YW2m0tk8TdVaXHlA==",
          "dev": true,
          "requires": {
            "commondir": "^1.0.1",
            "make-dir": "^1.0.0",
            "pkg-dir": "^3.0.0"
          }
        },
        "find-up": {
          "version": "3.0.0",
          "resolved": "https://registry.npmjs.org/find-up/-/find-up-3.0.0.tgz",
          "integrity": "sha512-1yD6RmLI1XBfxugvORwlck6f75tYL+iR0jqwsOrOxMZyGYqUuDhJ0l4AXdO1iX/FTs9cBAMEk1gWSEx1kSbylg==",
          "dev": true,
          "requires": {
            "locate-path": "^3.0.0"
          }
        },
        "locate-path": {
          "version": "3.0.0",
          "resolved": "https://registry.npmjs.org/locate-path/-/locate-path-3.0.0.tgz",
          "integrity": "sha512-7AO748wWnIhNqAuaty2ZWHkQHRSNfPVIsPIfwEOWO22AmaoVrWavlOcMR5nzTLNYvp36X220/maaRsrec1G65A==",
          "dev": true,
          "requires": {
            "p-locate": "^3.0.0",
            "path-exists": "^3.0.0"
          }
        },
        "p-limit": {
          "version": "2.0.0",
          "resolved": "https://registry.npmjs.org/p-limit/-/p-limit-2.0.0.tgz",
          "integrity": "sha512-fl5s52lI5ahKCernzzIyAP0QAZbGIovtVHGwpcu1Jr/EpzLVDI2myISHwGqK7m8uQFugVWSrbxH7XnhGtvEc+A==",
          "dev": true,
          "requires": {
            "p-try": "^2.0.0"
          }
        },
        "p-locate": {
          "version": "3.0.0",
          "resolved": "https://registry.npmjs.org/p-locate/-/p-locate-3.0.0.tgz",
          "integrity": "sha512-x+12w/To+4GFfgJhBEpiDcLozRJGegY+Ei7/z0tSLkMmxGZNybVMSfWj9aJn8Z5Fc7dBUNJOOVgPv2H7IwulSQ==",
          "dev": true,
          "requires": {
            "p-limit": "^2.0.0"
          }
        },
        "p-try": {
          "version": "2.0.0",
          "resolved": "https://registry.npmjs.org/p-try/-/p-try-2.0.0.tgz",
          "integrity": "sha512-hMp0onDKIajHfIkdRk3P4CdCmErkYAxxDtP3Wx/4nZ3aGlau2VKh3mZpcuFkH27WQkL/3WBCPOktzA9ZOAnMQQ==",
          "dev": true
        },
        "pkg-dir": {
          "version": "3.0.0",
          "resolved": "https://registry.npmjs.org/pkg-dir/-/pkg-dir-3.0.0.tgz",
          "integrity": "sha512-/E57AYkoeQ25qkxMj5PBOVgF8Kiu/h7cYS30Z5+R7WaiCCBfLq58ZI/dSeaEKb9WVJV5n/03QwrN3IeWIFllvw==",
          "dev": true,
          "requires": {
            "find-up": "^3.0.0"
          }
        },
        "source-map": {
          "version": "0.6.1",
          "resolved": "https://registry.npmjs.org/source-map/-/source-map-0.6.1.tgz",
          "integrity": "sha512-UjgapumWlbMhkBgzT7Ykc5YXUT46F0iKu8SGXq0bcwP5dz/h0Plj6enJqjz1Zbq2l5WaqYnrVbwWOWMyF3F47g==",
          "dev": true
        }
      }
    },

Also ng build --prod always stuck on 92% chunk asset optimization TerserPlugin for 1 minute. Not sure if it is related.

Does someone have any idea? Thanks.

[AudrenThibault]

Hello, I also have this problem after ng build --prod except that it’s not “undefined”.

this is the error :
“ERROR in scripts.e76817c8d2c56b2cd376.js from Terser Invalid assignment [scripts.e76817c8d2c56b2cd376.js:21,32]”

I tryed your solution @immad-hamid but it didn’t work for me…

[immad-hamid]

@mengzhen94 I have found the fix, it’s due to terser. If terser exist in your package.json file then downgrade it to “terser”: “3.14.1” without ^ and if you don’t see it in your package.json then it must be in package.lock.json, in this case do as follow:

Just add “terser”: “3.14.1” in your devDependencies in your package.json and npm install. You now would be able to make a production build without any issue.