Thank you Karlg100!!!
I had exactly the same problem. Well written instructions saved me time and frustration.
I wish I had see this before. I have trying to upgrade from 2.4 to 2.8 with no success. It took the 2.7 no problem.
@Nigel You can format the USB disk firstly in windows system and you can direct upgrade to V2.8. Thanks
Is formatting the USB disk a necessary prerequisite for upgrading to 2.8 ?
Tried that, it did not make any difference. The only way it would work was 2.4>2.7>2.8>2.9. Now happy at 2.9. If only I could get a test to work properly.
No, just format the USB disk when you encountered the problem.
Did that and used 2 other usb. It would not read the 2.8 file at all. As soon as I put the 2.7 on it all was good…