Dependency Version Conflict - Incompatible Package Versions
npm install fails or warns about version conflicts. Packages require different versions of the same dependency.
Error: 'peer dep missing' or 'conflicting peer deps'
Error Messages You Might See
Common Causes
- Two packages require different major versions of same dependency
- Peer dependency mismatch - library requires React 17 but you have 18
- npm version changed how it handles peer deps (npm 8+ is stricter)
- Dependency not compatible with Node version
- Outdated package not updated to support new dependencies
How to Fix It
Check what's conflicting: npm list [package-name]
Update package: npm update package-name@latest
If incompatible: remove older package and install newer
Force install (risky): npm install --legacy-peer-deps
Better: find package compatible with your versions or replace with alternative
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Get HelpFrequently Asked Questions
When should I use --legacy-peer-deps?
As temporary workaround only. Better to update packages to compatible versions. Don't commit with this flag
What's a peer dependency?
Library expects to use your version of a package (React, etc). You install it, library reuses it
How do I check all dependencies?
npm list shows tree. npm ls --depth=0 shows top level. npm outdated shows what can update