1. Install with legacy peer deps

Usually works immediately:

npm install --legacy-peer-deps

or:

npm i --legacy-peer-deps
2. Force install

Less safe but sometimes needed:

npm install --force
3. Delete lock + node_modules

Then reinstall clean:

rm -rf node_modules package-lock.json

npm install

Windows:

rmdir /s /q node_modules
del package-lock.json

npm install
Find the exact conflicting package

Run:

npm install

Then look for lines like:

Found: package-a@5
peer package-a@"^4" from package-b

That tells you:

You installed version 5
Another package only supports version 4

You then either:

downgrade package-a
upgrade package-b
use --legacy-peer-deps
Common real-world fixes
React conflicts
npm install react@18 react-dom@18
Next.js conflicts

Match versions:

npm install next@latest react@latest react-dom@latest
TypeScript conflicts
npm install typescript@latest
Check dependency tree
npm ls

or specific package:

npm ls react