Yeah, the main issue is migration (here in Germany). And I believe propaganda is also a factor. People are bombarded with bad stories about migrants, but also about the government. This includes tabloids and social media of course. But also the conservative opposition. They are always talking about the government as if it was the worst in German history, when in reality it is not so different from their previous one.
Btw. the reasons why people vote for extremists are not smart. They are emotional. AfD voters tend to be less educated and porer.