Create a reference all available block content In Drupal 7 there is Block Reference field module that can reference pretty much all available blocks, including views' blocks, system blocks, menu blocks etc.

I'm just starting with Drupal 8 and since the Block Reference module doesn't have a version for it, and the built-in Entity Reference doesn't seem to pick up views' blocks, system blocks, I want to create a new custom block type. In this new block type, I want to have a reference field that can reference all available block content.

Is there a way to do it?
Like I said, I'm new to Drupal 8 so not familiar with new rule and features. After a bit digging here is what I found out. 

Entity Reference field allows to reference block instances (config) or custom blocks (content). 

Before I was set my field to Content > Custom block, now I switch it to Configuration > Block then you have to Place the block that you want to reference to, even if it is in disabled. After that, you can have your Entity Reference field pick that up otherwise it won't show.

You can have a look at here for more detail.