Thank you very much for these usefull guidelines. I managed to fix the installation with your help.

Hi,
My Opera Mail has been running as a portableapps on a usb key. Now suddenly I get the message "omailbase.dat" failed to load during initialisation. Since my backup version gives the same error, I have a problem. Does some know what I could do ?

I'm running Opera 30 on a usb stick and have lost all my customization (bookmarks, extensions, speed dial, ...)
Copying the "data" directory from backup to the current usb installation is enough to restore my customized environnement at startup. But when I close and restart Opera I loose everything again. As far as I can see there is an automatic mechanism used by Opera to copy the "data" directory back and forth between its original place and "App/Opera". How can I prevent Opera to restore a "blank" environnement or so to say prevent it to reset the environnement to default settings ?