How to fix Cannot find module 'typescript' in Angular 4?

I generated Angular 4 app 3 weeks ago using the @angular/cli. After 2 weeks, I tried to run it with the command line ng serve but I am prompted an error below:

Cannot find module 'typescript'
Error: Cannot find module 'typescript'
    at Function.Module._resolveFilename (module.js:469:15)
    at Function.Module._load (module.js:417:25)
    at Module.require (module.js:497:17)
    at require (internal/module.js:20:19)
    at Object.<anonymous> (C:\Users\mypc\Documents\Angular Projects\my-angular-app\node_modules\@angular\cli\models\config\config.js:5:12)
    at Module._compile (module.js:570:32)
    at Object.Module._extensions..js (module.js:579:10)
    at Module.load (module.js:487:32)
    at tryModuleLoad (module.js:446:12)
    at Function.Module._load (module.js:438:3)

Do you have any idea how to fix this? Thanks.

11 thoughts on “How to fix Cannot find module 'typescript' in Angular 4?”

  1. I had the same problem. If you have installed first nodejs by apt and then you use the tar.gz from, you have to delete the folder located in /usr/lib/node_modules.

  2. I had a very similar problem after moving a working project to a new subdirectory on my file system. It turned out I had failed to move the file named .angular-cli.json to the subfolder along with everything else. After noticing that and moving the file into the subdirectory, all was back to normal.

  3. If you use yarn instead of npm, you can install typescript package for that workspace by running:

    yarn add typescript

    or you can install it globally by running:

    sudo yarn global add typescript

    to be available for any project.

  4. For me just running the below command is not enough (though a valid first step):

    npm install -g typescript

    The following command is what you need (I think deleting node_modules works too, but the below command is quicker)

    npm link typescript
  5. I had a similar problem when I rearranged the folder structure of a project. I tried all the hints given in this thread but none of them worked.
    After checking further I discovered that I forgot to copy an important hidden file over to the new directory. That was


    from the root directory of the @angular/cli project. After I copied that file over all was running as expected.

  6. Run: npm link typescript if you installed globally

    But if you have not installed typescript try this command: npm install typescript

  7. If you don’t have particular needs, I suggest to install Typescript locally.

    NPM Installation Method

    npm install --global typescript # Global installation
    npm install --save-dev typescript # Local installation

    Yarn Installation Method

    yarn global add typescript # Global installation
    yarn add --dev typescript # Local installation

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