July 28, 2017 Patch

{{Patch layout
 * source = http://store.steampowered.com/news/31172/
 * source-title = Portal 2 Update


 * before   = July 27, 2017 Patch
 * current  = July 28, 2017 Patch
 * after    = September 08, 2017 Patch


 * notes =

Portal 2
An update has been released for Portal 2.

}}
 * Show an error dialog if the game is launched while Steam isn't running.