Angular 5与Bootstrap 4版本兼容问题及npm启动报错求助

Hey there! Let's get this sorted out for you. The error you're seeing is pretty straightforward—your project is missing the local TypeScript package that @ngtools/webpack (which Angular uses under the hood) requires, and it's likely a version compatibility mismatch between Angular 5 and your dependencies. Here's how to fix it step by step:

1. Install the correct TypeScript version for Angular 5 #

Angular 5 is compatible with TypeScript 2.4.2 to 2.6.x (we'll go with 2.6.2, a stable, recommended version for Angular 5). Run this command in your project root to install it locally as a dev dependency:

npm install typescript@~2.6.2 --save-dev

2. Verify the installation #

Check if TypeScript is now properly installed in your project:

npm ls typescript

You should see the version 2.6.2 listed under your project's dependencies.

3. If issues persist, clean and reinstall dependencies #

Sometimes cached files or corrupted node_modules can cause problems. Follow these steps:

• Delete the node_modules folder:

  # On macOS/Linux
  rm -rf node_modules
  
  # On Windows Command Prompt
  rd /s /q node_modules
  

• Delete the package-lock.json file:

  # On macOS/Linux
  rm package-lock.json
  
  # On Windows Command Prompt
  del package-lock.json
  

• Clear npm's cache:

  npm cache clean --force
  

• Reinstall all dependencies:

  npm install
  

4. Addressing the version mismatch warning #

The warning about version mismatch can be suppressed with the command mentioned in the error:

ng set --global warnings.versionMismatch=false

But I'd recommend fixing the underlying dependency versions first instead of just hiding the warning—this ensures your project stays stable.

A quick note on compatibility: Your Node 8.11.1 and npm 5.6.0 versions are actually compatible with Angular 5, so the main issue here was definitely the missing/mismatched TypeScript package.

内容的提问来源于stack exchange，提问作者Santhosh