Angular CLI - Typescript throws: Cannot read property 'length' of undefined

Question

I run in angular 4 project with ng serve and i get error

Cannot read property \'length\' of undefined

but I don\'t have any property length in

Answer 1

My error was caused by c&p error when creating a small component. I forgot to change path to component's template and styles.

Answer 2

Close the running port and Try rebuilding the app with "ng build"

Answer 3

Could be bad path to component templateUrl, perhaps missing the ./

Before: templateUrl: 'my-control.component.html',

After: templateUrl: './my-control.component.html',

Answer 4

Most likely you have changed around your modules in a way that needs the CLI to be restarted.

I had the same error running ng serve after removing a component from a module. By restarting that process and re running ng serve the error went away.

Answer 5

In my case I did the following and it solved the issue:

1. Create environments folder (if not exist) in src of the Project C:\Users\abcd\Desktop\MyApp\src

2. Put the two files environment.ts and environment.prod.ts in environments folder.

Answer 6

In my case, it's mysterious. But it won't hurt to offer what I had witnessed and maybe a bit history. None or maybe some historical event might have caused it but I really don't know.

• Everything is good. Angular 8 running inside 18.04.4 LTS (Bionic Beaver)LXC within 19.10 ubuntu host with npm 6.14.2, node10.16.3
• Upgraded host to 20.04 LTS(Focal Fossa). Write some code. Remove a package called angular-shepherd. Try to build --prod. This errors shows up during angular Generating ES5 bundles.
• Tried everything. All failed.
• Reset what I did inside the project. Still fail.
• Reboot LXC.
• Fixed.