I started seeing this about an hour ago. I get an http code of 0 and no response from all queries related to friends and followers. Other queries are fine, so it isn’t my server, IP, or OAuth keys. This happens across all scripts and all apps, none of which have changed.
There appear to be some service issues right now which are likely causing this.
The API itself never sends HTTP status code 0. That’s an illusion presented to you by your HTTP library or programming language when it otherwise cannot connect.