Fix the upstream dependency conflict installing NPM packages

javascript

npm

package-management

dependency-conflict

byAnton Shumikhin·Feb 7, 2025

To fix a dependency conflict in NPM, run npm dedupe to correct duplicated dependencies or manually specify a version in package.json. Use this simple snippet to force a version:

"dependencies": {
  "conflicted-package": "x.x.x"
}

For Yarn users, a similar solution is to add a resolutions block for version overrides:

"resolutions": {
  "conflicted-package": "x.x.x"
}

This method makes the package manager use a specific version, thereby solving the conflict.

Understanding npm v7's peer dependency changes

npm v7 came with a change in handling peer dependencies which can cause conflicts during installation. The solution is running:

// NPM is "n" a "p"ain in the "m"aterial world? Try this!
npm install --legacy-peer-deps

By running this command, npm reverts to the peer dependency resolution strategy from npm v6, which doesn't auto-install them.

Overcoming specific conflicts and dependencies

Forcing the issue

If --legacy-peer-deps doesn't resolve the issue, here's a potential showstopper:

// "Brute force: If it doesn't work, you're just not using enough."
npm install --force

This overrides the package manager's usual safety checks.

Legacy everywhere

You can configure npm to use legacy peer dependencies for all installations:

npm config set legacy-peer-deps true

Manual meddling

If all else fails, you can manually specify the versions in package.json:

"overrides": {
  "mapbox-gl": "1.13.0"
}

Preventing conflict disasters

To prevent the apocalypse before it happens, remember to:

Avoid the "*" wildcard in package versions
Brush up on the npm v7 changes
Use npx create-react-app with the --legacy-peer-deps flag for new React projects