Ugraded to Angular 9: Error: Can't resolve all parameters for ApplicationModule: (?).

I upgraded my app to Angular 9 & am getting the following error:

Error: Can't resolve all parameters for ApplicationModule: (?).
    at syntaxError (/home/brian/work/dishzilla/menus-angular-2-app/apps/angular-app/dist/server.js:7582:17)
    at CompileMetadataResolver._getDependenciesMetadata (/home/brian/work/dishzilla/menus-angular-2-app/apps/angular-app/dist/server.js:27327:35)
    at CompileMetadataResolver._getTypeMetadata (/home/brian/work/dishzilla/menus-angular-2-app/apps/angular-app/dist/server.js:27219:26)
    at CompileMetadataResolver.getNgModuleMetadata (/home/brian/work/dishzilla/menus-angular-2-app/apps/angular-app/dist/server.js:27087:24)
    at CompileMetadataResolver.getNgModuleSummary (/home/brian/work/dishzilla/menus-angular-2-app/apps/angular-app/dist/server.js:26889:35)
    at /home/brian/work/dishzilla/menus-angular-2-app/apps/angular-app/dist/server.js:27008:51
    at Array.forEach (<anonymous>)
    at CompileMetadataResolver.getNgModuleMetadata (/home/brian/work/dishzilla/menus-angular-2-app/apps/angular-app/dist/server.js:26996:49)
    at CompileMetadataResolver.getNgModuleSummary (/home/brian/work/dishzilla/menus-angular-2-app/apps/angular-app/dist/server.js:26889:35)
    at /home/brian/work/dishzilla/menus-angular-2-app/apps/angular-app/dist/server.js:26981:55

I have spent hours debugging this issue, but still have not made progress. I’ve also seen a number of fixes for this error message in previous years but none of those solutions worked for me. Can you please advise on obtaining a better error message that is easier to debug, because this error message is not very helpful. Thank you

[celesteking]

In my case (Angular 6 -> 6.1 LTS upgrade), it was because some idiot added window.global = {window}; to index.html. Removing that cleared the error. Spent 4 hours trying to track this down. Angular sucks.

[btakita]

@AndrewKushnir Unfortunately, I cannot provide a simple reproduction due to the complexity of the app. I added some logging statements & noticed that when ReflectionCapabilities.prototype._ownParameters is invoked on the ApplicationModule reflection type, the logic falls through to the If a class has no decorators, at least create metadata case. [ undefined ] is returned since the constructor has an arity of 1.

https://github.com/angular/angular/blob/master/packages/core/src/reflection/reflection_capabilities.ts#L123

When @angular/core/fesm5/core.js is loaded. Here is the definition of ApplicationModule in that file.

var ApplicationModule = /** @class */ (function () {
    // Inject ApplicationRef to make it eager...
    function ApplicationModule(appRef) {
    }
    ApplicationModule = __decorate([
        NgModule({ providers: APPLICATION_MODULE_PROVIDERS }),
        __metadata("design:paramtypes", [ApplicationRef])
    ], ApplicationModule);
    return ApplicationModule;
}());

I’m not familiar with how to access the source of the ApplicationModule type object, as directly mutating ApplicationModule does not seem carry over to the type object passed to ReflectionCapabilities.prototype._ownParameters.

One thing I hope to get out of this issue is to identify the source of the problem & to have an error that directly notifies the programmer of the cause of the error.

I thought ivy was enabled by default on Angular 9. I admit that I don’t use Angular for most of my projects so I’m a bit out of the loop with the evolution of Angular & it’s various architectural updates. I’ll investigate if Ivy is being used…

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@ericmartinezr I noticed that you gave a thumbs down on this issue. I’d love to provide more detail about the reproduction, but I’ve been spending > 6 hours trying to identify the issue. Is this not an area that can be improved or am I supposed to “suck it up” & pretend that everything is ok or something like that? I’d rather there be a quicker way to fix this problem without the need to file an issue in the first place. Since this same error has been reoccurring for years (since v2), with multi-hour debug sessions, is this not an area that can be improved to help developers?