I ran into an issue today that took several hours to figure out. I searched everywhere for a similar issue and did not find any information. As a result, I wanted to share this to help anyone else that may have hit the same thing.
I had originally installed PhpStorm while logged in as a Domain user on my CentOS box. Found that it would be easier to use all of the tools (including webtools) if I switched to a local user.
I had removed PhpStorm from the original install and re-installed everything under the local user account. When configuring the PHP Interpreter I kept running into the error "PHP version: Not available" - it didn't matter what version of PHP I was trying to use. I tried completly removing PhpStorm and installing a clean version... still no luck.
After a bunch of digging I found that there are two .php scripts in the /tmp folder that PhpStorm uses ... one is required to get the PHP version when adding an interpreter. Both of these were created with permissions of the original domain account and were not accessible to the new local user account.
The two files are: /tmp/ide-phpinfo.php and /tmp/ide-phpunit.php
Once I changed the owner/group information to my new user I was finally able to add a PHP Interpreter!
I used dolphin as root to make the change but the following command will also work: sudo chown newuser:newgroup /tmp/ide-phpinfo.php
Hope this is helpful!