error with file upload

[Vindy]

I try to upload an image in VirtueMart-Shop-Vendor. When I press Save changes in all text fields are saved but in Mozilla I get empty page, in Chrome "Server Error 500". An image is not uploaded.
Joomla 3.4,6
VirtueMart 3.0.12

[jenkinhill]

This forum has an excellent search facility. It is located top right of this page......

http://forum.virtuemart.net/index.php?topic=132092
http://forum.virtuemart.net/index.php?topic=131754