Angular 10 upgrades appear to work quickly with little problems..
The Angular support folks read all issues and will respond quickly.

The Long Version

I became highly frustrated with an Angular 8 refactor project recently, I had seen everyone of these errors below. You know it's true because, nobody could just make up these awful messages?

ERROR in No NgModule metadata found for 'AppModule'

Cannot read property id of undefined

Cannot read property map of undefined

Accessor cannot be declared in an ambient context

Angular has no exported member

InjectionToken Function Calls are not supported

ERROR: Dependency @angular/animations must be explicitly whitelisted

An unhandled exception occurred: Configuration 'production' is not set in the workspace

Error: self signed certificate in certificate chain - without reporting where or what to look for

Cannot find a differ supporting object..

The effort to resolve them was two weeks! Having even tried a migration to 9.LTS; it made things worse. I almost made it but the Angular folks kept asking me if I updated to 10.0 because many of these were fixed. I'm sure many of the issues were somehow my fault, but I wasn't making much progress.

I gave it a shot, and the good news is that the Angular 10 upgrade experience was good. I did see peer dependency issues due to their calling out pre Angular 10 dependencies (was forced to ignore them). Two projects, one a library and the other an enterprise application were done in 2 hours!

The best part was after two weeks I was where I started, refactoring existing code.

JWP 2020