Package '@angular/cli' is not a dependency

Assuming you are upgrating from Angular 8.0 to Angular 9.0 follow the following steps:

 1. rm -rf node_modules package-lock.json
 2. npm install @angular-devkit/schematics@8
 3. ng update @angular/core@8 @angular/cli@8
 4. ng update @angular/core@9 @angular/cli@9

In case you face any Peer dependency warnings when running the commands above run npm uninstall affected_package_name and then run the steps below:

 1. npm i
 2. ng update @angular/core@8 @angular/cli@8
 3. ng update @angular/core@9 @angular/cli@9
 4. npm i compatible_affected_package_name

You can run npm uninstall @angular-devkit/schematics after successful update.

Note: Always follow the Angular update Guide. You can swap the current and target angular versions depending on your situation. Before moving to higher versions ensure that all of your dependencies can work on your target version.

I ran into this same issue/error message because I had switched branches that were drastically different and not yet run npm install on the branch to get the current version installed which at this point was Angular 7. After that completed, I ran the following again to install the latest version; Angular 8:

ng update @angular/cli @angular/core

This time the error did not appear and the upgrade was a success. It appears that the upgrade process is looking for valid files to know what version it's updating from, and if there is a missing or empty node_modules folder, Angular can't tell what exactly is being updated and will throw this error. It makes sense because the CLI behaves differently based on the old version being upgraded and how many versions are being updated, so if it has nothing to read from for upgrading it can't continue.

In my case it was missing node_modules folder. Make sure to run npm i before updating.

First commit all your changes to the repo and then try following commands.

npm i -g @angular/[email protected]

and

ng update --all --force

Please read this issue on github