System:
    OS: Linux 5.12 Arch Linux
    CPU: (8) x64 Intel(R) Core(TM) i7-4712HQ CPU @ 2.30GHz
  Binaries:
    Node: 16.5.0 - /usr/bin/node
    Yarn: Not Found
    npm: 7.17.0 - /usr/bin/npm
  Browsers:
    Chrome: Not Found
    Firefox: 90.0
  npmPackages:
    vue: ^2.6.11 => 2.6.14 
  npmGlobalPackages:
    @vue/cli: Not Found

[adq@shinyandchrome blah]$ npm add -D @vue/cli-service@^4.5.0
npm ERR! code ERESOLVE
npm ERR! ERESOLVE unable to resolve dependency tree
npm ERR! 
npm ERR! Found: vue@2.6.14
npm ERR! node_modules/vue
npm ERR!   vue@"^2.6.11" from the root project
npm ERR! 
npm ERR! Could not resolve dependency:
npm ERR! peer @vue/compiler-sfc@"^3.0.8" from vue-loader-v16@16.3.2
npm ERR! node_modules/@vue/cli-service/node_modules/vue-loader-v16
npm ERR!   optional vue-loader-v16@"npm:vue-loader@^16.1.0" from @vue/cli-service@4.5.13
npm ERR!   node_modules/@vue/cli-service
npm ERR!     dev @vue/cli-service@"^4.5.0" from the root project
npm ERR!     2 more (@vue/cli-plugin-router, @vue/cli-plugin-vuex)
npm ERR! 
npm ERR! Conflicting peer dependency: vue@3.1.5
npm ERR! node_modules/vue
npm ERR!   peer vue@"3.1.5" from @vue/compiler-sfc@3.1.5
npm ERR!   node_modules/@vue/compiler-sfc
npm ERR!     peerOptional @vue/compiler-sfc@"^3.0.0-beta.14" from @vue/cli-service@4.5.13
npm ERR!     node_modules/@vue/cli-service
npm ERR!       dev @vue/cli-service@"^4.5.0" from the root project
npm ERR!       2 more (@vue/cli-plugin-router, @vue/cli-plugin-vuex)
npm ERR!     peer @vue/compiler-sfc@"^3.0.8" from vue-loader-v16@16.3.2
npm ERR!     node_modules/vue-loader-v16
npm ERR!       optional vue-loader-v16@"npm:vue-loader@^16.1.0" from @vue/cli-service@4.5.13
npm ERR!       node_modules/@vue/cli-service
npm ERR!         dev @vue/cli-service@"^4.5.0" from the root project
npm ERR!         2 more (@vue/cli-plugin-router, @vue/cli-plugin-vuex)
npm ERR! 
npm ERR! Fix the upstream dependency conflict, or retry
npm ERR! this command with --force, or --legacy-peer-deps
npm ERR! to accept an incorrect (and potentially broken) dependency resolution.
npm ERR! 
npm ERR! See /home/adq/.npm/eresolve-report.txt for a full report.

npm ERR! A complete log of this run can be found in:
npm ERR!     /home/adq/.npm/_logs/2021-07-20T16_04_01_591Z-debug.log