Ubuntu / Mint : "error: symbol 'grub_efi_find_last_device_path' not found"

A few months back my working Ubuntu / Windows setup suddenly stopped working.  Ubuntu boots fine but trying to open Windows gave an error like this :

"error: symbol 'grub_efi_find_last_device_path' not found"

The cause here is a bug in grub2.  To fix force a downgrade to the previous version of grub2.

Some info here :

https://answers.launchpad.net/ubuntu/+source/grub2/+question/280812