I'm new to Linux and recently set up a dual-boot system with CachyOS and Windows on the same NVMe drive. During the Linux installation, I accidentally deleted Windows' 100 MB EFI System Partition, so the computer no longer boots into Windows and the Linux boot menu does not detect it. Most of the Windows installation and my files still appear intact when viewed from Linux.
I need to preserve my existing Windows data, settings, and modifications. I do not want to format the Windows partition, duplicate the installation, or perform a clean reinstall. I also have a Windows recovery point available. What is the safest way to recreate the EFI partition or repair the Windows bootloader using Windows installation or recovery media, while avoiding damage to the existing Windows installation and keeping Linux from interfering?
3 Answers
Before changing partitions or running repair commands, make an offline backup of anything irreplaceable if possible. Even though the files appear intact, boot-repair work can go wrong if the wrong partition is selected. A recovery point may help with system files, but it should not be treated as a complete backup of personal data and settings.
This sounds like a bootloader repair situation, not a Windows reinstall. You can boot from Windows installation or recovery media, open the recovery command prompt, and recreate the EFI boot files on a replacement EFI System Partition using the existing Windows installation. The Windows partition itself should remain untouched if you select the correct volumes and avoid formatting it. Search specifically for instructions on rebuilding a missing Windows EFI boot partition with the `bcdboot` command, and double-check the drive letters shown in the recovery environment because they may differ from normal Windows.
For future Linux experiments, using a separate drive for Linux—or temporarily disconnecting the Windows drive during installation—greatly reduces the chance of overwriting Windows’ boot files. Dual-booting does not require both systems to be installed on the same physical drive.
That makes sense. I had assumed both operating systems needed to share the same drive for it to count as dual-booting.