npm install - ERESOLVE unable to resolve dependency tree

Question

I am trying to npm install but getting this error.

npm ERR! code ERESOLVE
npm ERR! ERESOLVE unable to resolve dependency tree
npm ERR! 
npm ERR! While resolving: webapp@21.0.0
npm ERR! Found: @angular/cdk@9.2.4
npm ERR! node_modules/@angular/cdk
npm ERR!   @angular/cdk@"9.2.4" from the root project
npm ERR! 
npm ERR! Could not resolve dependency:
npm ERR! peer @angular/cdk@"8.2.3" from @angular/material@8.2.3
npm ERR! node_modules/@angular/material
npm ERR!   @angular/material@"8.2.3" 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.

Answer 1

I updated node.js to the latest recommended LTS version which is currently version 14. This is what is causing the problem.

I tried using --force and --legacy-peer-deps , but this didn't work.

The solution is to downgrade the node version to 12.

Here is a copy/paste solution to fix. Copy all of this code and paste in the terminal at the root of your project. (Where your package.json file that you are trying to install is.)

rm package-lock.json
rm -rfv node_modules
curl -o- https://raw.githubusercontent.com/nvm-sh/nvm/v0.38.0/install.sh | bash
export NVM_DIR="$([ -z "${XDG_CONFIG_HOME-}" ] && printf %s "${HOME}/.nvm" || printf %s "${XDG_CONFIG_HOME}/nvm")"
[ -s "$NVM_DIR/nvm.sh" ] && \. "$NVM_DIR/nvm.sh"
nvm install 12
nvm use 12
npm i

What is happening here?

1. Remove the package-lock.json file
2. Remove the node_modules directory ( -rfv = recursive, force, verbose)
3. Install nvm (Node Version Manager)
4. Configure nvm
5. Load nvm
6. Use nvm to install node v12
7. Tell this project to use node v12
8. Use npm to install the packages

Answer 2

try npm install --legacy-peer-deps . This worked for me. But first make sure you delete your package-lock.json and node_modules .