Some months back I got the message on my Lumia 640XL that I could try/move to Windows 10. I did, but since I have all my apps on SD card and the internal memory does not have enough memory to fit all apps, a lot of apps did not work anymore.
Luckily I could revert back and have Windows 8 again.
However, eventually I want to use Windows 10 again, but do I something wrong or do I have to wait until Windows 10 supports app storage on SD cards like Windows 8? For me, this is one of the key features I need.