[BUG] unable to resolve dependency tree

[lornally]

there is another bug, but has been closed.

Current Behavior:

npm install --save-dev webpack-dev-server

output:

npm ERR! code ERESOLVE
npm ERR! ERESOLVE unable to resolve dependency tree
npm ERR! 
npm ERR! Found: webpack@5.3.2
npm ERR! node_modules/webpack
npm ERR!   dev webpack@"^5.3.2" from the root project
npm ERR! 
npm ERR! Could not resolve dependency:
npm ERR! peer webpack@"^4.0.0" from webpack-dev-middleware@3.7.2
npm ERR! node_modules/webpack-dev-middleware
npm ERR!   webpack-dev-middleware@"^3.7.2" from webpack-dev-server@3.11.0
npm ERR!   node_modules/webpack-dev-server
npm ERR!     dev webpack-dev-server@"^3.11.0" from the root project
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 /Users/bergman/.npm/eresolve-report.txt for a full report.

npm ERR! A complete log of this run can be found in:
npm ERR!     /Users/bergman/.npm/_logs/2020-11-04T06_31_48_517Z-debug.log

Environment:

• OS: macos 10.15.7
• Node: 15.0.1
• npm: 7.0.3

[ljharb]

What happens with npm v7.0.8?

[lornally]

What happens with npm v7.0.8?

how can i install it? i install node, the npm is 7.0.3, how can i update it to 7.0.8?

[jonleopard]

@lornally You can grab the latest version of npm by running npm install npm@latest -g. After that's finished, run npm -v to confirm you have v7.0.8 installed.

[nlf]

we haven't actually tagged npm 7 as latest yet, but npm install -g npm@7 should do the trick for you

[billyjanitsch]

This seems like expected behavior. You have webpack@5.3.2 installed and you're trying to install webpack-dev-server@3.11.0 which transitively peer-depends on webpack@^4.0.0. These webpack ranges are incompatible, as the error mentions.

You can fix it by using webpack@4 instead of webpack@5. webpack-dev-server@3 is not compatible with webpack@5.

(IMO, npm's output here is not very friendly. It's nice that it identifies all of the relevant packages, but if I didn't know much about peer dependencies, I could imagine being quite confused about what's wrong and what to do next. The message doesn't explicitly mention that it's a peer dependency issue -- it says "peer" but it also says "dev" and many other things -- and "fix the upstream dependency conflict" is not actionable.)

[isaacs]

Working as designed, and better error messaging and handling in latest npm v7.

[mvyunko]

i had the same prob

npm install npm@latest -g
then
npm install webpack-dev-server --save-dev

working for me

[mihailthebuilder]

@nlf 's solution doesn't work for me but @mvyunko 's does. The latter downgrades npm from version 7 to 6 however.

[hosseinGanjyar]

I had same problem and have done these steps:

1. uninstall & install nodejs
2. npm install npm
3. npm install webpack-dev-server --save-dev

[tienphamminh]

retry this command with --force:
npm install webpack-dev-server --save-dev --force

[Moise10]

// This solved my problem
npm config set legacy-peer-deps true