IDE's Java runtime (1.8u111) is outdated - this may cause stability issues. Please update to 1.8.0u112 or newer while opening PhpStorm in Ubuntu 16.10

Start the IDE, use Help | Find Action (Ctrl+Shift+A or Cmd+Shift+A on Mac), type "Switch IDE Boot JDK", press Enter.

But If you don't have the latest JDK, download it from: Download latest JAVA JDK here

And then select the "IDE BOOT JDK" like Tall Liou told.