I was getting the dreaded error message too, but got it to work finally. The reason I think why it didn't work for some then later it did is because, like me people aren't entering their bootloader code into the website correctly
Copying and pasting from CMD (love linux) is tricky. What I did to make sure I got the code in a single line was to copy the code as a single line into wordpad first. To make it very clear you can change the page type under page setup to Legal and turn it landscape to give you lots of room to paste the long code. Then copy the code as a single line from wordpad into the website.
worked for me