Cannot read property 'visitExpression' of undefined

Question

In my angular app at the startup point I'm facing this error:

Cannot read property visitExpression of undefined

What could be the problem?

Answer 1

In my case, it was duplicate , in the Routes array in app.routing.ts.

You can use ,[\s]*, as a Regular Expression search query to find it in your routes to find two commas with (0 to many) white spaces in between them.

Answer 2

It was ',' in my case in app.module.ts file.

imports: [
    BrowserModule,
    **AppRoutingModule,,**
    HttpClientModule,

Changed it to:

imports: [
    BrowserModule,
    **AppRoutingModule,**
    HttpClientModule,

Answer 3

In my case, it was components with empty selectors.