since I am using WIN10 I have experienced problems with the buildin updater. It always displays "check your internet connection and firewall". Normally I hit "okay" and close the updater window with the "close" button. Somehow today I got the message that XMM is not running with admin rights. Starting XMM with admin right solves the update problem.
I would suggest to include this in the error message as well.
You are right, Ale should add that to the standard error message.
For me I always start XMM with admin rights to provide such problems.
Using a little trick via the task planner I am even able to start it without that boring UAC confirmation if I really wanna start the prog with admin rights. Two or three years ago I have made a program to create such a link to start a few often used progs out of the taskplanner. If you are interested in: http://www.mediafire.com/download/4zzm13pb74oaq26/TaskCreator.rar I use it under Win 7 as well as under Win 8. As I don't have Win 10 I don't know if it works well, too. So if you wanna give it a try...
In order to achieve what is possible, you have to try the impossible over and over again. Hermann Hesse