[solved] JomSocial - Group Categories - 500 Layout Default Not Foundjs-category-groups.png
I've found solution for you ...
1) Please download attached file -->
legacy.zip
2) Unzip
3) Use FTP Client to replace this same file from this folder:
libraries/legacy/viewp.s.
I think it was Joomla bug with legacy mode that's why JomSocial worked fine on J3.1.1 but not under J3.1.4/5. Or maybe JomSocial team forgot about advanced tests, who knows.
I don't know what will happen when you will use Joomla 3.2 in next ~9 days - but please don't rush.