I have a new hp laptop with Windows 10 and UEFI. I installed Ubuntu on an external SSD, and did the partitioning according to this How to use manual partitioning during installation?.
Everything worked fine as long as my SSD stayed plugd in. The problem was Ubuntu brought its own GRUB Bootmanager. If I removed the SSD and tried to boot my laptop, I went straight to GRUB command line, since it didn't find ubuntu. I couldn't reach the classic GRUB OS selection window. Only way to still use Windows was to plug the SSD back in.
After some research I performed this procedure to remove GRUB (willing to loose my access to Ubuntu on my SSD): https://smarttechnicalworld.com/remove-grub-bootloader-from-windows/
Now however I had this Problem: No Bootmanager Bootdevice detected It says: BootDevice Not Found Please install an operating system on your hard disk... I tried changing tons of settings in UEFI, like secure boot of fastboot, legacy boot, but it didn't help.
Using F12 or F10 on my hp laptop I found out that the Windows Bootmanager was deactivated (you can reactivate it by pressing enter on the grayed out options). So know finally I'm back to the same state as before (I hope this helps anybody else in this situation).
What could I have done different that this would have worked?, that I could have booted to windows when the SSD/Ubuntu wasn't detected? Would it have worked to set the ubuntu boot partition to the laptop HDD, so GRUB finds the OS and opens the OS selection window? or is there a built in Windows OS selction tool?
Did someone manage?
