Make ubuntu 20.04.2 desktop custom LiveCD encounter Check finished: errors found in 1 files! You might encounter errors

The reason why encounter error is that md5sum script in the Ubuntu LiveCD article.

This script in nowadays will product the isolinx directory md5sum. Which is not hash on official Ubuntu's 20.04.2 image.(Maybe the wiki need to be modified. You can see the beginning of article is ubuntu-18.04-desktop-amd64.iso. But end of article is ubuntu-9.04.1-desktop-i386-custom.iso.)

To avoid this problem. You can modified the script from

find -type f -print0 | sudo xargs -0 md5sum | grep -v isolinux/boot.cat | sudo tee md5sum.txt #original

to

find . -type f -not -name md5sum.txt -not -path '*/isolinux/*' -print0 | sudo xargs -0 md5sum | grep -v isolinux/boot.cat | sudo tee md5sum.txt #other people purposal

In this issue. It doesn't cause by the Windows rufus ESP problem. Althought the rufus may cause the same problem.(like @Akeo said. rufus update in 3.15. In this changelog)