Tried installing Windows 10 on a PC that has Ubuntu 16.04 installed. Ubuntu uses LVM and had /boot and /boot/efi partitions as separate disks. After i succesfully freed up some space (100Gb) for Windows, i tried to install it and failed after selecting free space for Windows installing. Backed up both /boot and /boot/efi folders, removed both partitions (except LVM ubuntu partition) and tried installing Windows again at the same place with Windows saying that my efi partition is in NTFS. So now i can't boot up, because i have no efi partition at all. How do i install windows in that state?
I've seen similar reports elsewhere. Apparently Windows, or at least the Windows installer, sometimes misdetects a Linux-created ESP as being NTFS. My suggestion is to back up the ESP, create a fresh FAT32 filesystem on it, restore its contents, and try again. (Be sure it's FAT32, not FAT16. Depending on the filesystem size, you may need to set this explicitly with the
-F option to
mkdosfs.) You'll need to edit
/etc/fstab to adjust the "UUID" (really a serial number) associated with
/boot/efi to get it to mount properly in Ubuntu when this is done.
If this fails, try this one more time, but this time, create the filesystem on the ESP using a Windows emergency disk. This may require jumping through some extra hoops, but I don't know the details of what you'd need to do, since I'm not familiar enough with the Windows tools.