Angular v9 issue: Cant resolve all parameters for h: (?, ?, ?)

Question

I'm having the following issue when running "npm start" in my angular application. This happened to me after upgrading from ng8 to ng9.0.1. (With angular 8 everthing its working)

• I do not have circular denpendencies (already tested)

• I'm using angular 9.

• I do not have abstract class ( https://angular.io/guide/migration-undecorated-classes )

• I already checked all my decorators

This happen, BUT the app render the header, and all the bootstrap effects, so my store is filled, but nothing happens.

ERROR Error: Uncaught (in promise): Error: Can't resolve all parameters for h: (?, ?, ?).
Error: Can't resolve all parameters for h: (?, ?, ?).
    at main.586bd40b7d54c49d4834.js:1
    at ci (main.586bd40b7d54c49d4834.js:1)
    at li (main.586bd40b7d54c49d4834.js:1)
    at main.586bd40b7d54c49d4834.js:1
    at ai.processProvider (main.586bd40b7d54c49d4834.js:1)
    at main.586bd40b7d54c49d4834.js:1
    at main.586bd40b7d54c49d4834.js:1

I do not know what else can I test, as you can see bellow, the error does not give me any useful information to debug. Thanks

SOLUTION:

Since angular version > 7, core-js/es7/reflect is not necessary in polyfill.ts, this solution (that is the most common in the stackoverflow's questions or github issues) did not worked for me, I'm using angular 9 (the problem started after upgrading from v8 to v9). I started looking deeper to my app files, and I realized that in one xxx.effects.ts file, I missed the @Injectable() decorator, after adding this decorator, the issue were solved. What is weird for me its why in ng8 did not throw this error. This was tested just in dev mode, not production.

Answer 1

SOLUTION:

Since angular version > 7, core-js/es7/reflect is not necessary in polyfill.ts, this solution (that is the most common in the stackoverflow's questions or github issues) did not worked for me, I'm using angular 9 (the problem started after upgrading from v8 to v9). I started looking deeper to my app files, and I realized that in one xxx.effects.ts file, I missed the @Injectable() decorator, after adding this decorator, the issue were solved. What is weird for me its why in ng8 did not throw this error. This was tested just in dev mode, not production.