If you save the configuration without choosing any Available "Sort-by" fields
Warning: Invalid argument supplied for foreach() in .../administrator/components/com_virtuemart/classes/ps_config.php on line 250
a simple IF would do the trick :)
Configuration of what? Please make description of posts a bit more detail.
Sorry, I thought it is obvious that Available "Sort-by" fields is in the VM Main Configuration (Site tab)...
It is obvious but always have to make sure.
Q&T note; tracker URL http://dev.virtuemart.net/cb/proj/tracker/itemDetails.do?task_id=1674