My errors npm ERR! peer dep missing: acorn@^6.0.0, required by acorn-dynamic-import@4.0.0 npm ERR! extraneous: ajv@6.9.1 /scan/node_modules/@angular-devkit/build-webpack/node_modules/ajv Try follows 1) npm install -g npm-check-updates 2) ncu -u 3) npm install 4) npm dedupe 5) npm prune --production 1),2),3) upgrade packages to lastest 4) remove duplicated packages 5) prune for removing extraneous