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Angular3 min read2026-03-01

Angular npm install Error: ERESOLVE unable to resolve dependency tree

Fix peer dependency version mismatches when installing Angular packages with npm.

Error Code / Stack Trace

npm ERR! ERESOLVE unable to resolve dependency tree

Problem Overview

npm install fails because an external Angular library expects an older major version of @angular/core than what is currently installed.

Why Does This Happen?

  • The third-party library has not yet published updates for the latest Angular major version.
  • Strict peer dependency enforcement introduced in npm v7+.

Step-by-Step Solution

Step 1: Install with --legacy-peer-deps

Bypass strict peer dependency resolution if the library is known to work.

bash
npm install --legacy-peer-deps

Step 2: Update Angular dependencies using ng update

Use Angular CLI's official migration tool to upgrade packages together.

bash
ng update @angular/core @angular/cli

Common Mistakes to Avoid

  • •Using --force instead of --legacy-peer-deps, which can introduce corrupted dependency trees.

Prevention & Best Practices

  • Check Angular compatibility matrices on npm before installing community UI packages.

Frequently Asked Questions

What does --legacy-peer-deps actually do?

It restores npm v4-v6 behavior, ignoring peer dependencies when installing packages.

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