Can someone explain what is the error here in below sentence?
Nowadays, several types of music genres, including, rock, hip-hop, R&B and country are becoming more popular across the world and which has sung in various languages.
One of a site which I did validation, it suggesting to change as below.
You either need an article with "more popular" or a plural form. Revise: "becoming a more popular" or "becoming more populars"
But then it looks odd to me if I change as suggested.