Could not resolve dependency when upgrading from Next.js 14 to 15 RC

[tjhoo]

Summary

Hi,

I'm trying to follow the steps here to upgrade Next.js 14 to 15 RC and encounter the following error

$ npm install next@rc react@rc react-dom@rc
npm ERR! code ERESOLVE
npm ERR! ERESOLVE unable to resolve dependency tree
npm ERR!
npm ERR! While resolving: [email protected]
npm ERR! Found: [email protected]
npm ERR! node_modules/react
npm ERR!   react@"19.0.0-rc-935180c7e0-20240524" from the root project
npm ERR!
npm ERR! Could not resolve dependency:
npm ERR! peer react@"19.0.0-rc-f994737d14-20240522" from [email protected]
npm ERR! node_modules/next
npm ERR!   next@"15.0.0-rc.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!

is this an expected error and we should specify --force when installing the RC packages?

npm install --force next@rc react@rc react-dom@rc

Additional information

No response

Example

No response

[icyJoseph]

Hi,

The problem is that, https://github.com/vercel/next.js/blob/canary/packages/next/package.json#L108-L109, lists those RC specific versions, as peerDependencies.

Eventually, when React 19 does stabilize, this won't be a problem, but as release day approaches, and new react, react-dom RC versions are publishes, Next.js is bound to lag slightly behind.

[tjhoo]

Yes, and we have specify --force when upgrading to Next.js 15.

The command has to be fixed in the upgrade guide

[judygab]

Specifying --force didn't work for me either, I still got errors. Is there anything else you tried?

[stoufa88]

I tried upgrading a barebone next 14 app to 15 and it worked with --force. pnpm also worked for me while showing these warnings:

 WARN  Issues with peer dependencies found . └─┬ next 15.0.0-rc.0 ├── ✕ unmet peer [email protected]: found 19.0.0-rc.0 └── ✕ unmet peer [email protected]: found 19.0.0-rc.0

[admintvalley]

same warning ┬ next 15.0.0-rc.0
├── ✕ unmet peer [email protected]: found 19.0.0-rc-6230622a1a-20240610
└── ✕ unmet peer [email protected]: found 19.0.0-rc-6230622a1a-20240610

[gumpsh]

Has anyone managed to sort this yet? npm error code ERESOLVE
npm error ERESOLVE could not resolve
npm error
npm error While resolving: @heroicons/[email protected]
npm error Found: [email protected]
npm error node_modules/react
npm error react@"19.0.0-rc-6230622a1a-20240610" from the root project
npm error peer react@"19.0.0-rc-6230622a1a-20240610" from [email protected]
npm error node_modules/react-dom
npm error react-dom@"19.0.0-rc-6230622a1a-20240610" from the root project
npm error 1 more (styled-jsx)
npm error
npm error Could not resolve dependency:
npm error peer react@">= 16" from @heroicons/[email protected]
npm error node_modules/@heroicons/react
npm error @heroicons/react@"^2.1.4" from the root project
npm error
npm error Conflicting peer dependency: [email protected]
npm error node_modules/react
npm error peer react@">= 16" from @heroicons/[email protected]
npm error node_modules/@heroicons/react
npm error @heroicons/react@"^2.1.4" from the root project
npm error
npm error Fix the upstream dependency conflict, or retry
npm error this command with --force or --legacy-peer-deps
npm error to accept an incorrect (and potentially broken) dependency resolution.
npm error
npm error
npm error For a full report see:

I have been trying all sorts of flags like --force, --legacy-peer-deps, -npm reinstall, --no-frozen-lockfile. I have also tried manually changing versions in the package.json, package-lock.json and yaml files. Nothing seems to work and my deployments are failing.

This is the dashboard project on the next.js getting started tutorial by the way.

I can launch the project from vscode and it all seems to run ok locally - but failing on the build I guess.

[laurenmacam]

using pnpm this worked for me:
delete pnpm-lock.yaml file
run
pnpm up next@rc react@rc react-dom@rc eslint-config-next@rc
pnpm i

[gumpsh]

Hi @laurenmacam - thanks for your suggestion. I did try it, but still getting issues unfortunately.

However, I finally managed to solve it by downgrading from next, react and react-dom rc versions to latest stable releases.

It was a real mission, but all test are passing on the Vercel deployment now, so I am happy!

[jastka4]

Adding this to my package.json helped with all the issues I had:

  "overrides": {
    "next": {
      "react": "^19.0.0-rc-a960b92c-20240819",
      "react-dom": "^19.0.0-rc-a960b92c-20240819"
    }
  }

You might want to change the version to the latest React RC version.

[gumpsh]

Yeah, will definitely be upgrading to latest version as soon as everything catches up with it - which may be the case already for all I know - I've been doing other things for a while!

[bugplanter]

npm i next@rc react@rc react-dom@rc eslint-config-next@rc --legacy-peer-deps

[jdhiro]

There is a reason legacy-peer-deps are legacy. This is a bad practice.

You'd be better off creating an overrides section in your package.json to deal with specific version overrides.