Comment 2 for bug 1313396

I ran into this when upgrading from 12.04 to 14.04 64 bit. Neither the release notes nor the upgrade instructions mention Wubi.

From the "Serious errors were found" prompt I went to manually check the filesystem, /host/ubuntu/disks/root.disk which turned out to be clean. Following some forum suggestions I edited the boot command line in grub to use 'rw' instead of 'ro' which allows boot to complete. Editing /etc/grub.d/10_lupin and running update-grub makes the change permanent so I can keep on booting. I don't know enough about the Wubi boot process to know if this is fixing the root cause or just a nasty workaround that could have unintended consequences.