Concerned about supervisor's poor level of knowledge on his students' research topics, and his reluctance to correct his knowledge - is this normal?
First thing: you are not alone. This kind of behaviour is very commom within the academia. 

In order to pursue a graduate degree you have to accept that your path will be both restless and lonely! Restless because you will discover a whole new word, full of opportunities and overshoots. On the other hand, you are going to have a master degree, so you have to do your dissertation alone. Yes, you SHOULD count on your advisor help, for sure, but you are supposed to do most of the work by yourself!

You can face your advisor lack of knowledge as another challenge to be overcome and start to either join a lab with people doing similar work or, in the worst case, you have an endless remote source of information out here. 

My greatest advice is for you to look up conferences within your field and be in contact with people that are doing similar work. It could help you a lot.