Working copy format has changed in Subversion 1.8, so after upgrading to TortoiseSVN 1.8 you should upgrade your working copies or checkout the new ones. After you've upgraded a working copy to the newer format, older Subversion clients will be unable to work with the upgraded working copy.
So, you've upgraded your working copy to the new format (SVN 1.8). It seems that another SVN client on your system is SVN 1.8 (e.g. TortoiseSVN 1.8.0?), but PHPStorm is still 1.7.x. SVN 1.7 can't work with 1.8 working copy and vice-verse.
See "Subversion 1.8 Release Notes | Upgrading the Working Copy".