Cannot find module '@angular/core' after upgrading to angular 9 and primeng 9

Question

I have upgraded to Angular 9, and updated PrimeNG to verion 9 . After I do ng build, I get the following errors, Cannot find module '@angular/core' in one of primeng library components. Both angular and primeng are version 9.0.0, what can be an issue?

Answer 1

删除 node_modules 和 package-lock.json 并重复安装

Answer 2

After you upgrade to primeng 9, check your project to see if it has old references to primeng components.

As an example please see attached, there are others that you need to change too, just look for them. Once you give correct reference, it will fix those errors for you. Another example is "growl" is depricated, change it to "toast".

Also make sure you import primeng modules correctly too.