Just to add to this, I also came upon this problem. My report server was working fine for months, I've got around 30 reports and make constant updates to them re deploying reports or creating new ones almost every week, however it just stopped deploying one day (although I could see them in the application we have bound them to)
The error was a 502 host not found. I have a feeling it was something to do with IT making changes in my company however all I needed to do to fix it was change the report server name to local host in the property settings.
Project / [Project Name] Properties
on the general tab in the TargetServerURL it used to say:
http://GSV-REP01/ReportServer
but then I changed it to this:
http://localhost:8080/ReportServer
and it started working again with no problems. Hope this helps someone, SSRS is a real pain sometimes.