How to fix TypeError: Cannot read property 'subscribe' of undefined

This issue means that something has been replaced with a mock object and returns a dummy result (undefined) instead of observable streams.

There is an answer for this error in the section called How to mock observables, if the error has been triggered by a mock service, and its property is of type of undefined.

Or you might check MockInstance or ngMocks.defaultMock in the case if the error has been caused by a mock component or a mock directive.